Morphological variability in Melampyrum

(Orobanchaceae)

Milan Štech

Faculty of Biological Sciences

University of South Bohemia

Czech Republic

Genus Melampyrum almost 40 species in northern hemisphere large morphological variation especially at

infraspecific level the indistinct species limits in some groups “seasonal variation” – the most conspicuous

phenomenon at the intraspecific level important fetotypic plasticity, influence of host plant

Interspecific level

Melampyrum nemorosum group

M. nemorosum group nearly one half of the genus´s species species delimitation is based predominantly on the

calyx indumentum, calyx teeth length, bract shape and bract colour, corolla length and corolla shape

but* characters indicated for individual species do not

correspond to reality sometimes* both infra- and interpopulation variation in these taxa

are large* populations with intermediate characters occur often

Example M. subalpinum / M. bohemicum many nomenclatorical and taxonomical mistakes originally described as M. nemorosum var. subalpinum

by Juratzka from the northeastern border of the Alps. Kerner included in your species M. subalpinum

(Juratzka) Kerner plants from Romania, which he himself described as M. bihariense later

Beck distinguished two types of M. subalpinum* M. subalpinum s. str. with wide leaves* M. angustissimum with narrow leaves

Kerner described M. bohemicum from the Czech Republic, but his diagnostic characters distinguish M. bohemicum from M. subalpinum s. str. and not from M. angustissimum

Diagnostic characters according to the Flora Europaea

Character M. subalpinum M. bohemicum

Leaf width (2–)14–18 mm 1,5–3 mm

Bracts ovato-lanceolate, deeply toothed, violet-blue

1,5–3 mm wide, green, the lower entire, the upper hastate-dentate

Calyx subglabrous glabrous or puberulent, but with longer hairs on veins and on margin

Calyx teeth 4 mm, more or less patent 4–6 mm, porrect

Corolla lenght 15 mm 18–20 mm

Study 26 morphological characters were studied in 15 populations of

M. bohemicum, M. angustissimum, M. subalpinum s. str., and M. nemorosum.

Differences in indicated diagnostic characters between M. bohemicum and M. angustissimum were not confirmed. M. bohemicum comprises a part of larger variation of populations of M. angustisimum.

M. subalpinum s. str. differs from both types and resembles M. nemorosum in some characters

Hybridization hypothesis intermediate position of M. subalpinum s. str. between

M. angustissimum and M. nemorosum large variation range in several characters among

individual populations of M. subalpinum s. str.

possibility of old introgressive hybridization between M. nemorosum and M. angustissimum

distribution area of M. subalpinum s. str.

Hybridization hypothesis intermediate position of M. subalpinum s. str. between

M. angustissimum and M. nemorosum large variation range in several characters among

individual populations of M. subalpinum s. str.

possibility of old introgressive hybridization between M. nemorosum and M. angustissimum

hybridization experiments indicate a possibility of successful crossing between M. bohemicum and M. nemorosum despite apparent reproductive barriers

distribution area of M. subalpinum s. str.

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M. bohemicum × M. nemorosum

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control without treatment

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control with removal of stamens

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0 = without capsule1 = regular capsule2 = aborted capsule

Melampyrum sylvaticum group

study* 17 morphological characters were studied in 25 populations of M.

sylvaticum in Central Europe

* RAPD markers were studied in 10 populations as a support of morphological study

M. sylvaticum group problem

* three taxa at the specific level are usually distinguished

* two taxa consider to be endemic in the Eastern and Southern Carpathians but occurrence records originate from other regions too

M. sylvaticum

M. saxosum

M. herbichii

Results M. herbichii seems not to be restricted in the Eastern and

Southern Carpathians Populations of M. sylvaticum agg. from the Western

Carpathians and Sudeten Mts. seem to be closer to M. herbichii based on the RAPD markers, but they are polymorphic and often similar to the M. sylvaticum s. str. from the morphological point of view

But problem is more comlex and needs further study

Discriminant Analysis – Canonical scores of individual plants on the discriminant axis.

Infraspecific level

Seasonal variation traditionally evaluated as the most important taxonomic

character at this level different populations of one species flower in different

periods of the year in addition to the flowering period so-called “seasonal

characters ” vary in different populations of one species

Example M. pratense probably the most variable species of genus many infraspecific taxa were described based on

seasonal characters mainly

study* 11 morphological characters were studied in 90 populations in

Central Europe

* changes in seasonal characters over the flowering period in particular populations and influence of enviromental factors were studied too

Results

Studied population form a very homogeneous reticulate pattern. Delimitation of intraspecific taxa based on the seasonal characters is impossible and would be artificial.

Populations of Melampyrum pratense break up into diverse “regional types” over all the distribution area. These types are characterised by a specific combination of seasonal characters, but also by other characters (the most conspicuous one is the flower colour).

Taxonomic description of these “regional types” is not much important, but processes generating this variation are worth of further study.

variation of “seasonal characters” is often limited by enviromental factors, which determined vegetation period length

Positions of individual plants in the ordination space of PCA of population samples. Two population examples are marked.

Example M. nemorosum 11 “seasonal characters ” were studied in 44 populations changes in seasonal characters over the flowering period in

particular populations and influence of enviromental factors were studied too

Results

* significant contrast were found in the seasonal variation pattern by comparison to M. pratense

* two seasonal taxa can be distinguished based studied morphological characters – early, late

* difference in habitat recquirements

Polytopic origin of early type is supposed

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late populations

Canonical discriminant analysis of plants of Melampyrum nemorosum. Frequency distribution of specimens along the canonical variable

Chance for further study study of the hybrifization hypothesis by molecular

methods revision of other confused taxa from the Melampyrum

nemorosum group origin of seasonal types by individual species study of important “nonseasonal characters” at the

infraspecific level (e. g. bract shape by M. pratense) phylogeographical study of selected species genus phylogeny …