Botanyforgardeners 2014
description
Transcript of Botanyforgardeners 2014
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Project SOUND
Out of the Wilds and Into Your Garden
Gardening with Western L.A. County Native Plants Project SOUND 2012 (our 8th year)
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Botany for S. CA
Gardeners Key Botanic Concepts to Improve Your Gardening
C.M. Vadheim and T. Drake
CSUDH & Madrona Marsh Preserve
Madrona Marsh Preserve
February 1 & 4, 2014
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California the land of extremes
Latitude
Elevation
Temperature
Precipitation
Soil type, content
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Thats part of the reason why my have so many unique
native plants
http://mapsof.net/uploads/static-maps/california_relief_map.png
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Botany: the study of plants (huge subject area)
I. Names, descriptions and taxonomy
II. Seeds A. How they develop
B. Dispersal
C. Germination
III.How plants grow
IV. Water & nutrients from the environment
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Todays talk
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Hollyleaf Redberry Rhamnus ilicifolia
2003 BonTerra Consulting
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Scientific names: why do we need em?
They are (or at least should be) universal
They are unique to a given taxon unlike common names like Wild pea or Wild sunflower
The name sometimes describes characteristics of the plants [ilicifolia = holly-like leaves] or honors the person who discovered them
The name (should) reflect the evolutionary relationships between it and other taxa
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Rhamnus ilicifolia
2006 Steve Matson
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Taxonomy & Systematics: grouping & naming
Taxonomy: science that finds, identifies, describes, classifies, and names plants
Three goals:
Identification : identifying an unknown plant by comparison with previously collected
Classification: placing known plants into groups or categories to show some relationship.
Description : formal description of a new species, usually in the form of a scientific paper
Systematics: the science of relationships between plants and their evolution, especially at the higher levels
Classical (morphological) systematics based on similarities in plant physical characteristics (how plant looks; chemical similarities; etc.)
Molecular systematics based on similarities in genetic material
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The two are highly interrelated both aim to better understand and reflect the true relationships between different plants
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Kingdom Plantae Plants Subkingdom Tracheobionta Vascular plants Superdivision Spermatophyta Seed plants Division Magnoliophyta Flowering plants Class Magnoliopsida Dicotyledons Subclass Rosidae Order Rhamnales Family Rhamnaceae Buckthorn family Genus Rhamnus L. Buckthorn Species Rhamnus ilicifolia Kellogg Hollyleaf redberrry
2005 James M. Andre http://seinet.asu.edu/images/vasc_herbarium_images/Rhamnaceae/photos/Rham_croc_SL_N0086.jpg
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Resources to help the confused gardener
USDA Plants Database: http://plants.usda.gov/java/
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The importance of higher taxa: insight
Family Rhamnaceae
Mostly trees/shrubs
Simple leaves, with stipules
Flowers usually small, inconspicuous [exception: Ceanothus spp.]
Fruits are mostly berries, fleshy drupes or nuts mostly dispersed by mammals and birds.
Chiefly used as ornamental plants and as the source of many brilliant green and yellow dyes
Project SOUND 2003 BonTerra Consulting
2005 James M. Andre
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The importance of higher taxa: insight
Genus Rhamnus Common name: Buckthorn
Usually deciduous CA has evergreen species
Fruit: berrylike, fleshy (edible?)
Wide light tolerance range
Generally drought tolerant once established
May be slow to get started then easy to grow
May cause mild dermatitis
Medicinal: prepared bark - purgative; laxative
Invasive potential: in Eastern U.S., exotic buckthorns (R cathartica; R. frangula) tend to form dense, even-aged thickets, crowding and shading out native shrubs and herbs
California members: Rhamnus (now Frangula) californica CA
Coffeeberry
Rhamnus crocea spiny redberry
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Spiny redberry
Rhamus crocea
http://biology.csusb.edu/PlantGuideFolder/RhamnusCrocea/RhamnusCroceaPage.htm
2002 Kristiaan Stuart
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The scientific name
The generic name is listed first (with its first letter capitalized), followed by a second term, the specific name (or specific epithet) and the name(s) of the first namer
International Code of Botanical Nomenclature specifies the format and conventions
U.S. Integrated Taxonomic Information System (ITIS) - facilitates sharing biologic info. by providing a common framework for taxonomic data
Sometimes regional experts dont agree with ITIS
Hollyleaf redberry Rhamnus ilicifolia Kellogg
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Calflora database: CA plants (native & not)
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What is a species?
Some definitions of species
Biological Species Concept - they cannot interbreed & produce viable offspring; interbreeding studies
Morphospecies Concept - they are different morphologically and do not come in contact for interbreeding
Genetic Species Concept still working on this how similar must they be to constitute a species?
Practical definition - Practically, biologists define species as populations of organisms that have a high level of genetic similarity.
The field of taxonomy is changing with our increasingly sophisticated tools
Lyonothamnus floribundus
ssp. aspleniifolius
Lyonothamnus floribundus
ssp. floribundus
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California (and other biologic hotspots) present more challenges
Lots of geographic/topographic variability
Relatively rapid environmental changes (since last Ice Age)
Lots of geographically separate populations are in the process of diverging
In other words, speciation is a work in progress
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2002 Kristiaan Stuart
http://biology.csusb.edu/PlantGuideFolder/RhamnusCrocea/RhamnusCroceaPage.ht
m
Rhamnus ilicifolia
Rhamnus crocea
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Why all the current taxonomic/systematic
arguments about CA native plants?
When two species have fully diverged from a common ancestor they will possess the properties commonly associated with independent species: reproductive incompatibility
distinctive morphology
ecological uniqueness.
During the process of divergence, these properties are gradually acquired in a continuum spanning thousands of years.
When two lineages are in the early stages of speciation it is difficult for biologists holding different species concepts to agree on when there has been enough divergence to declare them as different species.
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Whats a CA native plant gardener to do?
Keep calm this period of rapid change will end
Nurseries will likely know plants by both old and new name
Use on-line sources Native Plants at CSUDH
Scientific name - Scientific name key
Common name - Scientific name key
USDA Plants database
Calflora database
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http://www.zarachiron.com/2013/06/spanish-men-a-cultural-enigma/
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Native Plants at CSUDH - http://nativeplantscsudh.blogspot.com/
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Use the pages on left of screen
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Name to name lists are here
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The PLANTS
database
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Implications of plant taxonomy/systematics
for the gardener
Precise, scientific names are important:
For scientists including biomedical scientists working with plant-based medicinal chemicals, insecticides, etc.
For you as a gardener so you purchase the plant whose characteristics you want
Plant systematics provides insights
Understanding basic characteristics of groups requirements, susceptibilities, toxicities
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2002 Kristiaan Stuart
Rhamnus ilicifolia
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Implications of plant
taxonomy/systematics for the gardener
Conservation importance of conserving local endangered species in gardens, seed banks, etc.
Choice of appropriate plant species esp. if cross-pollination danger [Salvias; Buckwheats]
Evolution in the garden garden-friendly cultivars
(including novel hybrids)
Selection and climate change
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Plant anatomy and morphology:
describing plants
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Describing plants: what do those terms mean?
Stem: bark gray; branches stiff, generally ascending; twigs glabrous to finely hairy.
Leaf: evergreen; petiole 210 mm; blade 2040 mm, ovate to round, thick, glabrous adaxially, glabrous or hairy, flat to concave abaxially, base rounded, tip obtuse, rounded, or widely notched, margin entire, irregularly toothed, or prickly, veins prominent or not.
Project SOUND http://www.calflora.net/bloomingplants/hollyleafredberry.html
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Describing plants: simple leaves
Basic anatomy Petiole
Blade
Stipule
Veins Midrib
Veins
Shape terminology Overall shape
Blade tip
Blade base
Margins
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http://www.robinsonlibrary.com/science/botany/anatomy/leafparts.htm
Margin Blade tip
Base
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Simple vs.
compound leaves
Clues:
Look for an axillary bud (just above the midrib)
Look at old (or recently fallen) leaves the petiole separates cleanly from the branch (due to an abscission layer)
Use plant Family traits [Pea family (Fabaceae) usually have compound leaves]
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http://www.robinsonlibrary.com/science/botany/anatomy/leafparts.htm
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Describing plants: leaf shapes
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http://www.clemson.edu/extfor/publications/bul117/characteristics.htm
toothed http://www.nbh.psla.umd.edu/guides/appendix2.html
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Describing plants: what do they mean?
Stem: bark gray; branches stiff, generally ascending; twigs glabrous to finely hairy.
Leaf: evergreen; petiole 210 mm; blade 2040 mm, ovate to round, thick, glabrous adaxially, glabrous or hairy, flat to concave abaxially, base rounded, tip obtuse, rounded, or widely notched, margin entire, irregularly toothed, or prickly, veins prominent or not.
Project SOUND http://www.calflora.net/bloomingplants/hollyleafredberry.html
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Botanical terms/concepts & plant identification
Some excellent resources written specifically for the gardener
These 3 books are very good
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Help with terminology
Books Allaby, M : Oxford Dictionary
of Plant Sciences
Beentje, H : Kew Plant Glossary - an illustrated dictionary of plant terms
On-line: Several good resources good
for gardeners
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Weve tried to make using on-line resources easier by bringing together the best in one place Native Plants at CSUDH
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Let Native Plants at CSUDH help
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The Pages on the left of the screen provide helpful links to the Project SOUND/Out of the Wilds plant lists(under Plant Lists), gardening information sheets & plant photos (under Gallery of Native Plants)
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Gallery of Native Plants Native Plants at CSUDH
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There alphabetical name lists:
Scientific name to current sci name Common name to scientific name
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Native Plant Gallery Native Plants at CSUDH
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Click Save then choose to download or save. Youll be able to click on links
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Help make the
Gallery even better
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Send us your pictures of CA native
plants growing in garden settings
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Native Plants at CSUDH
http://nativeplantscsudh.
blogspot.com/
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Just search native plants at csudh with your favorite browser
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Were very familiar with the life stages of animals
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http://www.baby-connect.com/
http://onlinebusiness.volusion.com/articles/seniors-online/
http://fastfoodies.org/movie-food/elderly-people-on-computer/
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Plants have similar but different life stages
Fertilization
Embryogenesis/seed formation
Seed germination/early growth
Juvenile growth (vegetative)
Mature growth (vegetative)
Flowering/Fruiting/seed production
Senescence
Death
http://ww2.valdosta.edu/~ckbeck/ebook.html
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Describing plants: what do they mean?
Inflorescence: 16-flowered, generally glabrous; pedicel 24 mm.
Flower: generally unisexual; hypanthium 2 mm wide; sepals 4; petals 0.
Fruit: 2-stoned, 48 mm, red.
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Mark W. Skinner @ USDA-NRCS PLANTS Database
2002 Kristiaan Stuart
http://www.researchlearningcenter.org/bloom/species/Rhamnus_ilicifolia.htm
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Inflorescence: grouping/arrangement of flowers
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http://www.flowers-gardens.net/gardens/types-of-inflorescence.html
Wikipedia has a very good coverage of inflorescence terms
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Flowers are leaves specialized for reproduction
Calyx (whorl of Sepals) protect/attract
Corolla (whorl of Petals) attract
Stamen male sex parts Filament
Anther produces pollen
Pistil female sex parts Stigma receives pollen
Style channel
Ovary contains eggs which become seeds
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A perfect flower has all the parts
http://scienceblogs.com/pharyngula/2006/11/20/mads-boxes-flower-development/
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How does the pollen get to the stigma?
Falls on it
Physical agents Wind
Water
Biologic agents (Mother Natures cupids) Bees
Flies
Butterflies/moths
Other insects
Hummingbirds
Bats
Other animals
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Take-home messages: pollination
Getting the pollen to the egg isnt easy if youre a plant and you usually need a little help
The lives of plants and their pollinators are in intimately intertwined
Plants and animal pollinators have evolved together (co-evolution).
Plants usually dont waste energy on things they dont really need the color/scent etc. are there for a reason
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What are the likely pollinators of
Hollyleaf redberry?
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Pollination and
Fertilization
http://www.educationcaribbean.com/resources/encyclopaedia/science/plants.asp
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What does it take to form a seed?
Project SOUND http://www.bio.miami.edu/dana/226/226F09_4.html
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The unwritten goal of all living things:
reproduce and disperse
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Thats how species survive through time
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Why the need to disperse?
To colonize new areas which may have better resources or other advantages
To increase genetic diversity within the species or population novel combinations that may confer an advantage
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To decrease unhealthy competition (for light, water, other resources)
http://ebd10.ebd.csic.es/ebd10/Dispersal_and_gene_flow_files/shapeimage_2.png
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Dispersal is relatively easy if you have
legs or can swim
Project SOUND http://www.immortalhumans.com/early-man-had-the-same-life-span-as-neanderthals/
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Seed dispersal: traveling through space
Dropping to the ground
Catapulted from the dry seed capsule (fruit)
Carried by physical agents Floating on the wind
Carried by water
Carried by living agents Hitchhiking on animal fur, feathers
or feet
Travelling through a bird or animal for eventual deposition
Project SOUND http://science.psu.edu/news-and-events/2010-news/Carlo2-2010
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Clues to dispersal: often easy to read
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Box Elder Acer negundo
Jojoba - Simmondsia chinensis
http://www.arizonensis.org/sonoran/places/cavecreek.html
Size/weight
Flight/hitchhiking appendages
Inside a fleshy fruit
Characteristics of pod/capsule
CA poppy
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Others are a little more difficult
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http://www.arizonensis.org/sonoran/places/cavecreek.html
Yellow Paloverde Parkinsonia microphylla
Pea family Large, heavy seeds
Characteristic pod
Plant distribution in landscape Along seasonal streams
Seeds distributed by water
Effective for dispersing large, heavy seeds over wide area
Ensures that seeds will be dispersed at a time conducive to germination
Ensures that plants grow where best suited to survive
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Seed distribution implications for gardeners
Some seeds are born to naturalize: small seeds [annual wildflowers]; wind-born seeds [Milkweeds]
Plant species with fleshy fruits and youll attract fruit-eating birds & other dispersal agents
Remember, some seeds are meant to be carried in animal fur (clothing, etc.) [some grasses; cocklebur]
Plants with unusual dispersal mechanisms may require special treatments to encourage them to germinate
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http://dendro.cnre.vt.edu/dendrology/syllabus/fact
sheet.cfm?ID=491
Yellow Paloverde
Parkinsonia microphylla
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A seed is somewhat like a manned space capsule
A capsule with a protective covering
Containing A living organism: so dry that its in a state of suspended
animation
Provisions for the journey & for re-settlement
Traveling through space & time Project SOUND
http://millburyschools.sharepointsite.com/elmwood/lhippert/Picture%20Library74/Forms/DispForm.aspx?ID=3&RootFol
der=%2Felmwood%2Flhippert%2FPicture%20Library74%2F1 http://www.gijoecanada.com/index.php?main_page=product_info&cPath=71_76_
90&products_id=404
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The consequences of seed travel through
time and space
Must have adequate protection for wide range of possible conditions
Must have adequate provisions
Must provide everything needed to keep the living being alive until it reaches its final destination
Must keep the weight/size down (usually depends on dispersal)
Must not open the hatch-door until its reached its destination and conditions are favorable
Project SOUND http://www.ehow.com/info_8547249_stages-plant-reproduction.html
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The mighty seed
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http://generalhorticulture.tamu.edu/HORT604/LectureSupplMex07/HORT604Mexico2007.htm
Seed coat (testa) protective coat
Cotyledon/Endosperm - food source
Embryo
Radicle (embryonic root)
Hypocotyl/epicotyl (embryonic root/shoot)
Plumule (embryonic shoot/leaves)
http://www.cmg.colostate.edu/gardennotes/137.html
monocot seed (corn)
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Overview of Embryonic Development
http://www.pnas.org/content/107/18/8063/F1.expansion.html
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A completely mature, dry seed remains in
a state of suspended animation sometimes for a very long time
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Seed germination: complex process
What were interested in today is how does a seed begin the germination process and what does it need to survive as a seedling
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Koning, Ross E. 1994. Seeds and Seed Germination. Plant Physiology Information Website. http://carlsbadcommunitygardens.org/2013/04/2nd-annual-carlsbad-seed-swap-at-the-smerdu-community-garden/
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You may have noticed that fresh seeds
often germinate more easily
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but most seeds dont germinate prematurely. Why?
http://viviparouscapsicumfruitescens.blogspot.com/
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The timing of germination is critical
Must be adequate resources for the seedling to survive: Water
Light
Nutrients
Possibly other
Must not have future conditions that will kill a young seedling (seedling stage is the most vulnerable life stage): Too low or too high
temperatures
Drought
Fire
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California poppy - Eschscholzia californica
Immediate
future
Slightly
longer range
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Plants have developed several strategies
to prevent premature germination
Seed quiescence : delay germination because the external environmental conditions are not right : too dry or warm or cold for germination [most annuals; many fresh woody plant/perennial seeds]
Seed dormancy : seed is unable to germinate in a specified period of time under environmental conditions that are normally suitable for the germination of the non-dormant seed [many woody plant species normally facing challenging conditions]
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Several different processes: separate but
often interrelated
Seed germination: Depends on both external (environment) and internal (embryonic)
conditions [seed maturity]
Environmental: water, oxygen, + temperature, light
Seed quiescence: Depends on factors in the seed itself suspended animation
Released when proper conditions for germination are present
Seed dormancy: Depends on factors within the seed itself (but may require
environmental cues that promote it)
Released by exposure to proper environmental conditions (the triggers) which break dormancy and allow germination
Germination will not occur unless dormancy is broken
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Quiescence: a temporary hold on germination
Often due to seed dehydration
Seeds in state of suspended animation ; ready to germinate once environmental conditions change for the better The seed reaches soil
The first rain
The temperature warms up
Etc.
The risks associated with quiescence strategy: premature germination if conditions again change for the worse [hot, dry conditions after the first rain]
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ZZZzzzzzz
http://unrealnature.wordpress.com/2008/10/27/some-assembly-required/
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Dormancy: longer term strategy
Is a characteristic of the seed itself (not the environment); some seeds [those from tropical regions; typical garden plant seeds] exhibit no dormancy
Some CA native seeds are dormant when they leave the plant (primary dormancy) insures dispersion will occur prior to germination
Others only become dormant only when they experience unfavorable conditions (too dry; too hot or cold) secondary dormancy
Difference between fresh seeds and older seeds is usually explained by secondary dormancy
Dormant seeds will not germinate unless dormancy is broken
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Germination and dormancy are two
different processes
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http://www.rtbg.tas.gov.au/index.aspx?base=332
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The life cycle of seeds: mediterranean climates
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http://www.rtbg.tas.gov.au/index.aspx?base=299
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Why is seed dormancy important?
Ensures time for seed dispersal
Prevents germination during unsuitable ecological conditions
Enables seeds to survive short periods of favorable conditions; when germination stimulating factors are present, but prevailing conditions are not suitable for subsequent seedling growth and plant development.
Prevents germination of all the seeds at the same time. The staggering of germination safeguards some seeds and seedlings from suffering damage or death from short periods of bad weather, transient herbivores, etc
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In other words, the dormancy evolved as a mechanism to
postpone germination until a time and place that not only
supports germination, but also maximizes seedling
establishment and growth.
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Seed dormancy: many variations
Seed coat-imposed dormancy [AKA Exogenous/External dormancy] - caused by an impermeable seed coat
Embryo-imposed dormancy [AKA Physiological/endogenous/ internal dormancy] caused by the embryo itself; prevents embryo growth and seed germination until chemical changes occur within the embryo not due to any influence of the seed coat or other surrounding
tissues
most abundant form of seed dormancy in angiosperm
thought to be due to the presence of inhibitors, especially ABA, as well as the absence of growth promoters, such as GA (gibberellic acid).
Combinations why its sometimes hard to determine the factors needed to break dormancy in a given species
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Seed coat-induced dormancy: several
common mechanisms
Seed coat prevents water or oxygen uptake: [waxy coatings; special layers in seed coat that block water]
Hard seed coat prevents embryo from growing/emerging [coat must be softened/broken by exposure to stomach acids; mechanical means]
Seed coat contains growth inhibitors [must be leached away be repeated rinsing; exposure to chemicals that break down the inhibitors]
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Seed coat-induced dormancy: breeching
the seed coat
Seed coat must be broken down to allow entry embryos will germinate readily in the presence of water and oxygen once the seed coat and other surrounding tissues are either removed or damaged.
Is usually all or none: once seed coat is breeched theres no turning back so timing is critical
Typically found in species from the families Fabaceae, Malvaceae, Chenopodiaceae, and Liliciae
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http://www.seedsplants.kimeracorporation.co
m/articles/19-come-seminare-.html
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Scarification: breaking/fracturing seed
coat to facilitate water/gas uptake
Mechanical : tumbling, abrasion, nicking, pounding etc.
Chemical : usually involves acid treatment like concentrated H2S04 (sulfuric acid), other acid treatments
Physical : hot water treatment; other heat treatment (burning)
Soaking/leaching : some seeds
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http://www.organicgardening.com/learn-and-grow/pretreatments-slow-
germinate-seeds
http://mpgranch.com/staff-blogs/tales-of-a-
transplant/scarification-and-stratification.aspx
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Treatments to break embryo-induced
dormancy vary by plant
Common requirements/ treatments
Drying [after-ripening]
Low temperatures [stratification]
Alternating soaking/drying
Applied by mother nature or by the propagator
Clues from the native environment of the plant
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Hollyleaf redberry grows
in dry places, often with
colder winters may require stratification
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Chilling (stratification): exposure to cold-
moist conditions
Prevents temperate climate seeds from germinating until the spring
Temperatures: 0-10 C (32-50 F)
Time: usually 1-3 months; seed supplier may specify
Seeds need to be fully hydrated stratify in moistened vermiculite or moist paper towel/coffee filters in refrigerator
Need access to oxygen (air)
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Garden collected seed may want to wash first in mild (5%)
bleach solution to prevent fungal
contamination
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Some environmental conditions that break
embryo-induced dormancy in CA native plants
Drying [after-ripening - grasses]
Low temperatures [stratification]
High temperatures [heat stratification]
Light (or dark) exposure
Fluctuating temperatures (repeated heating and cooling over many months-years),
Fire/smoke chemicals
Freezing/thawing (may require cycles)
Passage through the digestive tracts of animals/birds
Removal/breakdown of fleshy fruit
Acid treatment
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Important points about CA native seeds
They differ in the amount of stored food Small amounts - must start producing quickly
Large amounts live off stored food for a while
They differ in the composition of their seed coat some are harder than others
They germinate in response to cues (all seeds) Water cue + softens coat (all plants)
Oxygen
Light (small seeds)
+Temperature
Some seeds are actually dormant until awakened by environmental exposures
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Implications for gardeners: seeds
Storage: Store seeds cool and dry
In general, smaller seeds have shorter shelf-life than larger seeds
Planting: Know if your seeds need pre-
treatment to break dormancy Seed company instructions
On-line
Inference: place of origin; taxonomic
Plant seeds at the correct depth some need light to break dormancy
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http://www.sierraclubgreenhome.com/go-green/landscaping-and-outdoors/organic-seeds/
Once seeds have germinated,
be sure to keep them adequately
watered very vulnerable to dehydration
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Be patient: just because you dont see anything, doesnt mean nothing is
happening
Root development may occur before shoot development particularly in large seeds [acorn]
Dormancy due to germination inhibitors may take some time
Cycles of hot and cool
Cycles of wet and dry
Many washings to leach away or chemically modify the inhibitors
Project SOUND
http://www.roguehydro.com/germinating-your-seeds/
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How do plants grow? By adding modules
All plants are based on same basic pattern: Shoot system
Main stem
Laterals (branches)
Root system Primary root
Lateral roots
Project SOUND http://leavingbio.net/flowering%20plants.htm
http://en.wikipedia.org/wiki/Plant_stem
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Shoot and root elongation and development
is segmental in plants
Phytomere: developmental segment for shoot (shoot module) or root (root module)
Phytomeres develop from unspecialized cells in special areas of the plant the apical meristems
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Plant meristems: the plants fountain of youth
Apical meristems (shoot and root) At the shoot and root tips
Give rise to the shoot or root modules
Result in elongation
Axial meristems Located at/near a node
Give rise to branches
Lateral meristems Located internally in
shoots/branches
Responsible for growth in girth
Project SOUND http://vannocke.hrt.msu.edu/plb865/31oct/meristems.html
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What do the meristems look like?
Central area with lots of simple cells
Surrounded by area of smaller cells (due to cell division)
Cells are more specialized looking (and larger) the further away from the meristem they are
Project SOUND
http://www.sbs.utexas.edu/mauseth/weblab/webchap6apmer/6.1-1.htm
http://mrzacbio.blogspot.com/
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All cells, tissues & organs arise form cells
in the apical meristems
Can traced origins back to the meristems
Fate maps can be drawn to trace the evolution of developing tissues
Apical meristem contains
Concentric rings of cells
Outer-most rings (segments) form lowest sets of leaves/stem segments
Pattern of development is somewhat like the water coming out of a fountain
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Phyllotaxy the arrangement of leaves on the stem
Is genetically determined thats why its often used in taxonomy & plant keys
Is determined by how much each new segment is offset around the stem
Project SOUND http://www.ecotree.net/fall_2011.shtml
http://everydayfibonacci.tumblr.com/
http://www.biologie.uni-hamburg.de/b-online/virtualplants/ipi_ic2.html
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Leaf arrangement/position (in relation to
others) phyllotaxy
Project SOUND
2009 Robert Steers
2002 Kristiaan Stuart
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Why do plants grow (at least in part) by
adding new segments?
Because thats how they evolved
Efficiency: particularly in an ever-changing environment
Redundancy/backup : plants need to be able to regenerate lost parts
As a consequence of a need for rigid structure
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http://www.calflora.net/bloomingplants/hollyleafredberry.html
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Plant cells are a little different from our cells
One of the big differences is that they form cell walls
Primary cell wall Formed first just inside the
cell (plasma) membrane
Strong but flexible
Allows for growth in certain directions (for example, cells can elongate)
Secondary cell wall Formed inside the primary cell
wall
Very strong; inflexible
No growth after secondary cell wall is formed
Project SOUND
http://acseenotes.wordpress.com/2011/03/07/cytology/
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What the heck! Why would plants do that?
Strong cell walls give plants the structure needed to grow tall
But plants still need to keep growing
Solution: add new segments on top of the old requires apical meristems Project SOUND
http://www.doitpoms.ac.uk/tlplib/wood/structure_wood_pt2.php http://montessoriworkjobs.blogspot.com/2011/10/human-skeleton.html
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Consequences of sedentary life: scary!
Plants need to keep rejuvenating themselves throughout life roots and shoots
Therefore they continue to grow throughout their lives sometimes for 1000+ years
In order to grow they need functional meristems [plant stem cells]
But what happens when something happens to an apical meristem (disease; herbivory)?
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Ancient (senescent) Bristlecone pine
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Fortunately, plants have a backup system
In most plants most of the time segments are added by the apical meristems
But there are backup meristems the axial meristems
Development of axial meristems is limited to a degree by the functional apical meristem produces an inhibitory hormone
Once the apical meristem is gone, the axial meristems take over the job of elongation
Project SOUND http://vannocke.hrt.msu.edu/plb865/31oct/meristems.html
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The shapes of plants
http://www.wildmanstevebrill.com/JPEG'S/Plant%20Image
s/Chicory.Rosette.jpg
http://www.unc.edu/~hallman/cookbook/pumpkin-vine.jpg
http://www.co.columbia.wi.us/dept/lwcd/images/tree.gif
http://www.houstonrose.org/ghbush.jpg
Stem elongation and control of the number of main shoots
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The length of the internode is one
determinant of plant shape
Project SOUND
http://www.doyletics.com/digest51.shtml
The main difference between the shape of a cabbage and a Southern honeysuckle vine is the length of the internodes
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The length of the internode: genetics and
environment
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2009 Robert Steers
Southern honeysuckle - Lonicera subspicata
Turkish rugging - Chorizanthe stacticoides
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Take home messages
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The basic structure (growth pattern/shape; mature size) is genetically determined. Choose plants accordingly
Butplants have enough flexibility programmed in to allow them to modify their shape based on conditions:
Limited water/nutrients shorter internodes
Limited light longer internodes as plant reaches for the sun
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But internode length doesnt explain all of the shape variability
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Torrey pine - Pinus torreyana Lemonadeberry Rhus integrifolia
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Apical dominance:
not all or none
Several plant hormones involved degree of apical dominance depends on balance of these
Degree of apical dominance is genetically determined thats why a pine tree has a strong central leader and a shrub has many equal stems
You can (sometimes) make a strongly dominant form more shrub-like; its more difficult to go the other way around
Project SOUND
http://plantphys.info/apical/apical.html
http://www.tutorvista.com/content/biology/biology-iv/plant-growth-movements/growth-
regulators.php
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Tip-pruning (pinching) removes apical dominance creating a bushier plant
Just remove the tip dont need to take much
Must be done during periods of active growth
Must do repeatedly for best effects new side branches will also exhibit apical dominance
Project SOUND
http://www.studyblue.com/notes/note/n/botany-exam-3/deck/1607515
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How far back can I safely tip prune/ prune to
head back?
Lateral buds have an age oldest at the base of a stem/trunk and youngest at the top
How long do lateral buds retain the ability to grow? Alas, no one answer.
But there are some rules of thumb: Generally - but not always lateral
buds in older woody parts of stems have decreased/no growth potential
Generally but not always buds in semi-soft or soft wood (younger parts of stem) will grow
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Take home messages: pruning/shaping
When shaping woody plants, start when plants are young
Know taxa that require careful pruning: Ceanothus spp
Arctostaphylos spp
Salvia spp
Pinus spp
Prune difficult species either:
During growth period (when wood is still semi-soft) for tip-pruning
When you can clearly apply the leave 3-4 leafing buds rule
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What materials do plants need from their environment?
Sunlight Photons of light (energy for
photosynthesis)
Air Oxygen (to break down stored
food)
Carbon dioxide (CO2) (for photosynthesis)
Soil/medium Water
Nutrients (minerals/ fertilizer)
Project SOUND
http://www.nelsonthornes.com/secondary/science/scinet/scinet/plants/nutri/c
ontent.htm
How do these move around the plant?
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Roots (root hairs) are where water and
minerals enter the plant
Good soils contain what plants need:
Water
Mineral nutrients (dissolved in the soil water)
Oxygen (needed by the roots so that they can obtain energy & perform their functions)
Project SOUND
http://www.aaronthomaslandscapes.com/blog.html
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The importance of soil water/oxygen balance
Too much water Root oxygen depleted decreased uptake of water, minerals
Too little water Roots cannot uptake water or dissolved minerals
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http://www.stevenswater.com/articles/irrigationscheduling.aspx
Thats why the symptoms or over- and under-watering are the same
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Root characteristics: especially important
with CA native plants
Coastal sage scrub shrubs Primarily fibrous roots
Primarily shallow roots (< 3 ft)
Root:shoot ratio increases with water & nutrient stress
Chaparral shrubs Combination of deep and
shallower roots
Root growth in spring/ summer
Root:shoot ratio increases with water & nutrient stress
Project SOUND
http://www.rmrs.nau.edu/watersheds/highlands/vegetation/chaparral/chpla
ntwater.html
Individual species have
characteristic root growth patterns
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Root characteristics of some common CA
native shrubs
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Use root characteristics to choose the
proper plant and treat it well!
Taproot Likely very drought-tolerant
Plant is out young dont move
Not for containers
Fibrous roots Look for depth characteristics
Shallow
may need occasional or regular water
Take care when digging
Good for containers
Good choice for slopes, banks
Lignotuber Fire-adapted; may require occasional
rejuvenation Project SOUND
http://nativeplants.msu.edu/getting_started/how_to_plant/establishment_
of_rooted_plant_material
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Well discuss roots more next month
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Development of the
vascular system
New segments of vascular system are added by apical meristems
New layers of vascular tissue in older segments are added by lateral meristems (called vascular cambium)
http://cnx.org/content/m43140/latest/
http://cnx.org/content/m47400/latest/?collection=col11569/latest
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Project SOUND http://www2.puc.edu/Faculty/Gilbert_Muth/phot0010.jpg
http://sci.waikato.ac.nz/farm/content/plantstructure.html
Benefits Two systems in close
physical proximity key to water/nutrient movement
Easy access for loading & unloading throughout the plant
New tissue can be added even in woody parts
Somewhat protected (fiber cap; bark)
Drawbacks Vulnerable location
Location of
vascular tissues
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Take-home messages: plant vascular system
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Soil water status is important not only for plant water needs, but also for mineral nutrition more next month
Plant vascular tissues move all sorts of vital things around the plant body an intact system is a must
Vascular tissues are vulnerable: Girdling
sucking insects [aphids]
Transport of toxins
http://caseytrees.org/blog/summer-tree-care-making-gardening-and-lawn-
care-safe-for-trees/
https://extension.umd.edu/learn/homeowner-landscape-series-common-
cultural-and-environmental-problems-landscapes-hg201 http://cnx.org/content/m47400/latest/?collection=col11569/latest
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We hope you look at plants differently
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Read a botany book
Use on-line resources and refer others to them
Come back next month when we consider the effects of climate change
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