—Plant—
Pl. Syst. Evol. 204:39-48(1997)
SystematlCS
and
Evolution
© Springer-Verlag 1997
Printed in Austria
Comparative embryology of three
Gentianaceae
species
from the Central Caucasus and the European Alps
Maja Akhalkatsi
and
Johanna Wagner
Received November
27, 1995;
in revised version April
11, 1996
Key words:
Gentianaceae, Gentiana pyrenaica, Gentianella caucasea, Gentianella ger¬
manica.
-
Functional embryology, antipodals, endosperm, life history, seed development.
Abstract: A comparative investigation was carried out on the ovule and seed develop¬
ment of three mountain species
of Gentianaceae,
the perennial species
Gentiana pyrenai¬
ca,
and the two short-lived monocarpic species
Gentianella caucasea
and G.
germanica.
In all three species most embryological characters conform to those generally found in the
family of the
Gentianaceae.
In some features, however, G.
pyrenaica
and the two
Gentia¬
nella
species differ from each other. In G.
pyrenaica
the ovule is anatropous, the integu¬
ment
8-10
layered and the three reduced antipodals degenerate soon after fertilization. In
contrast, G.
caucasea
and G.
germanica
form a hemitropous ovule, a
4-5
layered integu¬
ment and up to
16
antipodal cells by secondary multiplication. All three species exhibit
differences in synchronization between embryogenesis and endosperm development.
Functional relations between the antipodal structure and the dynamics of seed develop¬
ment of the investigated species are postulated.
The genera
Gentiana
and
Gentianella
together comprise about
450
species, dis¬
tributed mainly in mountain regions of Asia, Europe and America
(Meusel
&
al.
1978).
Most
Gentiana
species are perennials, whereas
Gentianella
species are
annuals, biennials or short-lived perennials. Up to now, embryological investiga¬
tions have been carried out on only about
30
species of these two genera
(Shamrov
1987).
In most cases they conform to the general embryological characteristics of
Gentianaceae.
Structural features vary in some details, however, providing valu¬
able characters for classification.
In the present study, ovule and seed development of the perennial species
Gen¬
tiana pyrenaica
L., and the short-lived monocarpic species
Gentianella caucasea
(Loddiges
ex
Sims) Holub
and
G. germanica
(Willd.)
Börner
are characterized and
compared. To our knowledge
G. pyrenaica
and
G. caucasea
have not been inves¬
tigated previously, and for
G. germanica
only the female gametophyte has been
described
(Guerin
1903).
Both
Gentianella
species are rather similar in habit and
morphological traits but occur as numerous ecotypic variants with different flow¬
ering times. Therefore investigating the extent to which these species share
embryological characters seemed worthwhile. On the basis of the embryological
profile of the three investigated species, possible connections between the structur-
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