Walsura
Description
Trees, unbranched low down or (if tree less than 4 m tall) densely twiggy at breast height, sympodial, leptocaul to pachycaul, buttressed or not.
Leaves usually all along leafy twigs, unifoliolate or imparipinnate with opposite leaflets, 1–4-jugate, to 80 cm long; rachis swollen slightly at the node(s); petiolule usually swollen slightly immediately beneath base of lamina and sometimes slightly geniculate; lamina apex acuminate to obtuse to retuse and base symmetric or slightly asymmetric, abaxial surface glaucous (in vivo) and glabrous to velutinous and sometimes with small glandular bodies (black dots) on either side of and within 2 mm of the midrib.
Inflorescences axillary (cauliflory unknown), 0.8-30 cm long, each a thyrse with a very dense to open paniculate head.
Flowers hermaphrodite or unisexual, just prior to opening ± cylindrical and up to 6 mm long, at maximum opening up to 9 mm diam., short pedicel widening almost imperceptibly into calyx.
Petals 5, free, valvate to imbricate, oblong to narrowly elliptic, apex acute to obtuse and sometimes hooded after opening.
Ovary very densely hairy with short erect trichomes or glabrous, 2-locular, each locule with 2 collateral ovules.
Fruit a l–2(–4?)-seeded berry or 1- or 2-seeded weakly dehiscent septifragal capsule, pericarp leathery with thin layer of sclerenchyma on inside, thin septum separating locules.
Seeds ellipsoidal, lacking endosperm surrounded by transparent sweet fleshy aril.
Distribution
from Assam, the Andaman Islands and tropical China, southeastwards to the Philippines and extreme western Irian Jaya present
16 species (including 3 insufficiently known ones) from Assam, the Andaman Islands and tropical China, southeastwards to the Philippines and extreme western Irian Jaya. Walsura does not occur naturally in Java or Sumatra.
Ecology
Walsura dehiscens is the only species known to have a dehiscent fruit. It is not yet known how this affects seed dispersal but berries of the other species have a succulent, sweet aril and are readily taken by birds and gibbons. Squirrels will eat the aril of these berries and discard the seed and pericarp.
Morphology
Aestivation may vary considerably within a single specimen (from valvate to imbricate) and although much used in the past as a character in this genus, is considered to be of little taxonomic value. A far better character is the proportion of the total androecium length (excluding anthers) which is a tube.
The glaucous (in vivo) or matt (in sicco) appearance of the abaxial surface of the leaf is due to a papillate epidermis, a feature only found in Walsura, Heynea (2 spp. in Indomalesia) and Ekebergia (4 spp. in Africa) in the Trichilieae.
Bark morphology seems to be of some taxonomic value but observations are few, and for some species completely lacking.
All species seem to lack exudate of any sort in slash bark or wood. However, most of the species have glands on the undersurface of the leaf and, since they exude small quantities of sweet colourless liquid, are probably best regarded as extrafloral nectaries.