Family Rousseaceae

Rousseaceae Hook. f. ex Benth.

Including Carpodetaceae

Habit and leaf form. Small trees, or shrubs; laticiferous (Abrophyllum), or non-laticiferous and without coloured juice (?). To 8 m high. Leptocaul. Mesophytic (in warm temperate and subtropical rain forest, along small water courses). Leaves medium-sized (about 10–20 cm long, 4–10 cm wide); alternate; spiral; flat; ‘herbaceous’ (thin); shortly petiolate (petioles 2–4 cm long); non-sheathing; simple; epulvinate. Lamina entire; elliptic to ovate, or lanceolate; pinnately veined; attenuate at the base. Leaves exstipulate. Lamina margins distally shortly dentate, or serrate; flat. Leaves without a persistent basal meristem. Domatia occurring in the family; manifested as pockets (i.e., in Carpodetus).

General anatomy. Plants with laticifers (Abrophyllum), or without laticifers (?). The laticifers of Abrophyllum in stems (there being in the pericycle a ring of laticiferous sacs consisting of longitudinal rows of vertically elongated cells). Plants with ‘crystal sand’ (in the leaves of Abrophyllum), or without ‘crystal sand’ (the rest?).

Leaf anatomy. Stomata present; mainly confined to one surface (abaxial); “with pairs of small guard-cells nearly circular in outline” (Metcalfe and Chalk). Hairs present; eglandular and glandular (the latter with short, sunken stalks and unicellular heads in Abrophyllum).

Lamina dorsiventral (with a single palisade layer in Abrophyllum).

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite; homostylous. Floral nectaries present. Nectar secretion from the disk (but the disk inconspicuous).

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in corymbs and in panicles. The ultimate inflorescence unit cymose. Inflorescences terminal and axillary; terminal or axillary corymbose panicles, these irregulary dichotomous and much shorter than the leaves. Flowers small (4–5 mm long); regular; 5(–6) merous; tetracyclic. Free hypanthium absent. Hypogynous disk present; intrastaminal (inconspicuous); annular.

Perianth with distinct calyx and corolla; 10–12; 2 whorled; isomerous. Calyx 5(–6); 1 whorled; very short, gamosepalous; toothed (the lobes deciduous); tubular; regular; non-accrescent. Corolla 5(–6); 1 whorled; polypetalous; valvate (the petals ultimately spreading); regular; yellow (-ish); plain; deciduous; non-accrescent. Petals sessile; entire.

Androecium 5(–6). Androecial members free of the perianth; all equal; free of one another; 1 whorled. Stamens 5(–6); isomerous with the perianth; oppositisepalous; alternating with the corolla members; filantherous (with very short filaments). Anthers basifixed; non-versatile; dehiscing via longitudinal slits; introrse. Pollen shed in aggregates (in Carpodetus), or shed as single grains (?); when in aggregates, in tetrads (Carpodetus).

Gynoecium 5 carpelled. Carpels isomerous with the perianth, or reduced in number relative to the perianth. The pistil 5 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 5 locular; sessile. Gynoecium shortly stylate. Styles 1; attenuate from the ovary; apical. Stigmas 1; 5 lobed. Placentation axile. Ovules 10–50 per locule (i.e., many); funicled; horizontal; apotropous; biseriate; non-arillate; anatropous.

Fruit fleshy; indehiscent; a berry (this about 8–12 mm long, ovoid, black). Seeds endospermic. Endosperm oily (and fleshy). Seeds small (subglobose, with a deeply latticed testa). Embryo well differentiated (but very small). Cotyledons 2. Embryo straight.

Physiology, biochemistry. Polyacetylenes not found.

Geography, cytology. Paleotropical, Australian, and Antarctic. Warm temperate and sub-tropical. Eastern Australia (Abrophyllum), New Zealand (Carpodetus), Mauritius (Roussea).

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Rosiflorae; Saxifragales. Cronquist’s Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; campanulid; Order Asterales.

Species 3. Genera 3; Abrophyllum (A. ornans), Carpodetus (C. serratus), Roussea.

Illustrations.
• Technical details: Abrophyllum ornans.
• Abrophyllum ornans, fruiting: photo, P. Woodard.

Miscellaneous. This description was prepared by LW in 2009 with reference mainly to Abrophyllum, and the morphology needs checking against Roussea and Carpodetus. It also lacks information on anatomy, anther development, pollen, phytochemistry and (especially) embryology. For example, if the family is really “Asterid” (i.e., Tenuinucelli, = Sympetalae), it is probably tenuinucellate with unitegmic ovules (etc.).