5. Xylosma G. Forster, Fl. Ins. Austr. 72. 1786.
柞木属 zuo mu shu
Apactis Thunberg; Hisingera Hellenius; Myroxylon J. R. Forster & G. Forster (1775), not Linnaeus f. (1782), nom. cons.
Shrubs or small trees, usually dioecious, rarely polygamous; trunk and branches usually spiny. Leaves alternate, stipulate, usually petiolate; leaf blade pinnate-veined, margin serrate, rarely entire, teeth glandular. Flowers hypogynous, small, in axillary fascicles, short racemes, or panicles, rudiments of opposite sex usually absent; bracts small, persistent or caducous; pedicels articulate at base. Sepals 4 or 5, imbricate, free or connate at base only. Petals absent. Disk extrastaminal, or in female flowers extragynoecial, comprised of several small closely set or connate glands (usually in staminate flowers) or annular (often in pistillate flowers). Staminate flowers: stamens ca. 10 to many, exserted; filaments free, filiform; anthers small, basifixed, sometimes apiculate by extension of connective. Pistillate flowers: ovary superior, 1-loculed; placentas 2(-6), each with 2 to many ovules; styles 2 or 3(or 4), often very short, joined in lower part only or completely joined to form a single style column, or styles absent; stigmas semilunate to U-shaped. Berry small, ca. 1 cm or less, pericarp thinly leathery, blackish when dried; disk and calyx often persistent at base; styles and/or stigmas persistent at apex. Seeds few.
About 100 species: tropical and subtropical regions, rarely extending to warm-temperate regions; three species in China.
The gender of the name Xylosma is feminine; see Art. 62.2(b) of the Vienna Code.
In Chinese species: stamens 10-20, filaments glabrous; ovary glabrous; berry red or black when fresh. See notes on identification under Flacourtia.
Differentiation between fruiting material of Xylosma controversa and X. longifolia can be difficult when the calyx is absent (caducous) and the critical sepal indumentum character therefore unavailable. Ranges of other character states (e.g., leaf size, shape, lateral vein number) overlap, and lateral veins are difficult to count in dried material, especially toward the leaf apex. Characters used previously, for example dried leaf color, leaf shininess, leaf base shape, and style length, are not reliable. For some fruiting material examined for the Flora (at K), identification of X. controversa has been based solely on the absence of the calyx. Further study is required to test the strength of this character and, ideally, provide additional ones.