Sonneratia in Flora of China @ efloras.org

9. Sonneratia Linnaeus f., Suppl. Pl. 38, 252. 1782.

海桑属 hai sang shu

Authors: Haining Qin, Shirley A. Graham & Michael G. Gilbert

Blatti Adanson.

Trees, evergreen, glabrous, columnar or spreading, not buttressed, surrounded by pencil-like pneumatophores arising from long, shallowly buried, horizontal roots. Leaves simple, opposite, borne in one plane, entire, leathery, apex often with a minute hydathode forming a thick mucro. Flowers 1-3 clustered at apex of ultimate, pendulous branchlets, actinomorphic, 4-8-merous, opening at night. Floral tube shallowly campanulate, at fruit maturity persistent, partly surrounding fruit or expanded and saucer-shaped with fruit fully exposed; sepals 4-8, adaxially green or red, thick, leathery. Petals red or white, lanceolate-linear, caducous, vestigial, or absent. Stamens numerous; filaments red or white; anthers reniform. Ovary superior to partly inferior, depressed, 10-20-carpellate. Fruit globose, berrylike, leathery, indehiscent, crowned by style base. Seeds numerous, embedded in foul-smelling pulp, irregularly angular or falcate; seed coat thickened, roughened, somewhat corky. 2n = 24.

Nine species (including three natural hybrid species): mangrove communities from E Africa to Indo-Malesia, Australia, New Guinea, and the W Pacific islands; six species (one endemic, one introduced) in China.

Hybridization among species is reportedly common, although molecular studies on Chinese populations of Sonneratia ×gulngai and S. ×hainanensis concluded that these species exist only as repeatedly produced F₁ hybrids. No evidence of F₂ backcrossing or intercrossing among the hybrids led to the conclusion that S. ×gulngai and S. ×hainanensis should not be considered true hybrid species (see Zhou et al., Molec. Phylogen. Evol. 35: 595-601. 2005).

1 Leaves narrowly elliptic to lanceolate, gradually tapering toward apex; calyx lobes 4(-6); stigma peltate, to 7 mm in diam., initially cone-shaped, spreading with age; petals absent; stamens white. 1 S. apetala

+ Leaves elliptic to broadly ovate, oblong, obovate, or suborbicular; calyx lobes 5-8; stigma capitate, mostly up to 3 mm in diam.; petals present or absent; stamens red, white, or red and white (2)

2 (1) Floral tubes flattened, saucer-shaped in mature fruit; mature flower buds and fruit wider than subtending persistent floral tube, mature fruit typically more than 4 cm in diam.; leaves broadly elliptic or oblong, base rounded, attenuate to petiole, apex rounded with minute mucro; petals and stamens red; sepals adaxially green or sometimes red-streaked. 2 S. caseolaris

+ Floral tubes campanulate and partially enclosing mature fruit; mature flower buds and fruit narrower than floral tube, mature fruit typically less than 4 cm in diam.; leaves various; petals and stamens white or red; sepals adaxially strongly tinged red (3)

3 (2) Floral tubes finely verruculose, dull, 6-ribbed; leaves broadly ovate to suborbicular, 4-10 × 3-9 cm, base rounded or subcordate, apex rounded, without thick mucro; petals mostly absent, rarely vestigial, white; staminal filaments white. 3 S. ovata

+ Floral tubes smooth, often shiny, sometimes 6-ribbed; leaves elliptic, suborbicular, ovate, or obovate, 5-11 × 2.5-8 cm, base rounded or attenuate, apex rounded with or without thick, recurved mucro; petals present, white or red; staminal filaments white or red (4)

4 (3) Leaves broadly elliptic or suborbicular, rarely broadly ovate, 6.5-8 × 6-8 cm; petals and staminal filaments white. 4 S. ×hainanensis

+ Leaves elliptic to ovate or obovate, 5-11 × 4-8 cm; petals and staminal filaments white or red (5)

5 (4) Petals white, presence and number variable; staminal filaments white, sometimes pink at base; leaves adaxially pale, whitish when dry; seeds falcate. 5 S. alba

+ Petals red, always present; staminal filaments red; leaves adaxially dull green; seeds irregularly angular. 6 S. ×gulngai

Lower Taxa

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