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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
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.
Nu
mb
er
of
de
ve
lop
ed
ca
ps
ule
s
M. bohemicum × M. bohemicum
20
45
7
0 1 20
20
40
60
80
100
120
M. bohemicum × M. nemorosum
1824 21
0 1 2
control without treatment
99
18
1
0 1 20
20
40
60
80
100
120
control with removal of stamens
27
13
0
0 1 2
0 = without capsule1 = regular capsule2 = aborted capsule
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.
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
Num
ber
of p
lant
s
0
20
40
60
80
100
120
140
160
180
200
220
240
-5 -4 -3 -2 -1 0 1 2 3 4
early populations
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 …