Abstract Detail

Developmental and Structural Section

Endress, Peter K. [2], Lorence, David H [1].

A novel type of heterodichogamy in Hernandia (Hernandiaceae).

Heterodichogamy of a novel type is reported in the family Hernandiaceae (Laurales). In Hernandia nymphaeifolia, which has unisexual flowers and is monoecious, two kinds of individuals were found, o­ne kind with female flowers open in the morning and male flowers open in the afternoon, and the other kind with the reverse behavior. The flowers, which are arranged in compound thyrses, form cymes of two male and o­ne female flower. Developmental studies confirm an earlier interpretation of these triads as monochasia with the sequence male - male - female (Kubitzki 1969). However, the sequence of anthesis is reversed: most triads flower with the sequence male - female - male. Flower development shows that the gynoecium is unicarpellate (not pseudomonomerous). In male flowers there are three rudimentary mounds (as yet overlooked) alternating with the stamens, which may correspond to those mounds in the female flowers that are united into a ring-shaped nectary and may represent extremely reduced staminodes. As heterodichogamy appears to be a rare phenomenon in angiosperms, it is of interest that heterodichogamy, although of a different type, has long been known in some Lauraceae, the sister (either alone or with Monimiaceae s.l.) of Hernandiaceae. For an evolutionary understanding, the flowering behavior of the other genera of Hernandiaceae should be studied.

1 - National Tropical Botanical Garden, 3530 Papalina Road, Kalaheo, Kauai, Hawaii, 96741-9599, USA
2 - University of Zurich, Institute of Systematic Botany, Zurich, CH-8008, Switzerland

Keywords:
floral development

Hernandia
Hernandiaceae
Heterodichogamy
Lauraceae
Laurales
nectaries
unisexual flowers.

Presentation Type: Paper
Session: 1-9
Location: Alpine A (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 10:30 AM
Abstract ID:888