The epicalyx in fruits of Scabiosa and Tremastelma (Dipsacaceae): Anatomy and significance behaviour.

Autor(en)

Veronika Mayer

Abstrakt

The fruits of Dipsacaceae exhibit a special type of epicalyx which encloses the fruit s.str. (pericarp and seed) with a +- strongly sclerified tube. In the present study the anatomy and functional bearing of the epicalyx was investigated in 23 species of Scabiosa and in the monotypic genus Tremastelma. In these genera the apical part of the epicalyx tube bears a thin membranous corona, while the calyx itself is modified into +- longspiny bristles. Mass analysis reveals that there is a striking correlation between perennial/annual growth and epicalyx fruit s.str. ratio. With few exceptions, in the perennial species the epicalyx makes up 30-50% of the whole fruit mass. In contrast, in the annual species of Scabiosa sect. Trochocephalus, the epicalyx may reach 70% of the whole fruit mass. The increasing mass proportion of the epicalyx is caused by an increase of sclerification of the tube: in addition to the original ring of longitudinal lignified fibres a second (inner) ring of sclerenchyma is developed. This second ring consists of horizontal lignified fibres and exhibits varios degrees of elaboration. In conducting germination experiments a correlation between tube sclerification and germination can be established: increase of sclerification (particuarly thickness of the innner ring) causes a delay in germination up to several days slowing down the water uptake. The functional significance of this feature in respect to plant habit and habitat conditions will be discussed.

Organisation(en)

Journal

Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie

Band

117

Seiten

333-357

Anzahl der Seiten

25

ISSN

0006-8152

Publikationsdatum

1995

Peer-reviewed

Ja

ÖFOS 2012

106008 Botanik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/0b38dbdb-a582-4805-ac3e-f7c134338b19