Hugonioideae

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Hugonioideae

Description

Trees or lianas, rarely shrubs. Hairs, if present, simple, uniseriate, or multi-seriate with multicellular, glandular heads. Leaves simple, spirally or distichously arranged, pinnately nerved. Stipules lateral, caducous. Inflorescences an axillary or terminal compound panicle, raceme, corymb, or cyme, or an axile fascicle, few- to many-flowered, rarely 1-flowered. Flowers actinomorphic, pentamerous, bisexual, hypogynous, sometimes heterodistylous. Sepals basally shortly connate or free, quincuncially imbricate, subequal or unequal, flabel-lately nerved, persistent, often slightly indurated and enlarged in fruit. Petals free, rarely basally clasping, shortly or not clawed, contorted, flabellately nerved, caducous. Stamens 10, alternately shorter and longer; Ovary superior, 3-5(-8)-celled; Ovules 2 per cell, axile, collateral, pendulous, epitropous. Fruit a drupe, rarely splitting in pyrenes. Seed(s) 1 or 2 per cell, arillode hardly or not developed.

Distribution

Asia-Tropical: Australasia:, Queensland (Queenslandpresent) Madagascar: present New Caledonia: present Old World tropics: present Pacific:, Fiji (Fijipresent) Pantropical: present Solomon Islands: present tropical South America: present
Pantropical; 5 genera, of which 2 small (Hebepetalum, Roucheria) confined to tropical South America, 1 (Philbornea) confined to Malesia, 1 Indo-Malesian (Indorouchera), and 1 in the Old World tropics (Hugonia, incl. Durandea), including Madagascar, with some three dozen species, eastwards extending as far as the Solomon Islands, Queensland, New Caledonia, and Fiji. In Malesia in all 5 spp.

Anatomy

The Hugonioideae are leaf anatomically very strictly defined by their shared possession of subsidiary cells which are lobed underneath the stomatal guard cells and cris-tarque cells (cells with Ca-Oxalate crystals and a unilaterally thickened, sclerified cell wall); para-cytic stomata are another constant feature of the group. This very unusual combination of characters induced VAN WELZEN & BAAS (1984) to advocate family status for Hugoniaceae, because the Linoideae (or Linaceae) lack this combination of characters. Most Hugonioideae have lignified guard cell pairs, but Indorouchera constitutes an exception and can be separated from the other two Malesian genera on account of its unlignified cells.
The wood anatomy of the Malesian Hugonioideae is incompletely known. Indorouchera has been recorded to have exclusively scalariform perforations; in Hugonia they are simple. The fibres have distinctly bordered pits like in all members (families or subfamilies) of the Linaceae sensu lato.
- P. BAAS

Phytochemo

See .