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Plant systematics and evolution - Comparative embryology of three Ge... (1997)
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—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-