Spiraeanthemum

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Spiraeanthemum

Description

Shrubs or small to medium-sized trees. Leaves simple, opposite and decussate, the margin entire or crenate-serrate; Stipules interpetiolar, one pair per node, simple, triangular-ovate, caducous. Inflorescences axillary and solitary or occasionally two subunits serially inserted, rarely terminal, paniculate, with branching at proximal nodes opposite and decussate and at peripheral nodes ± alternate, many-flowered, with peduncles 1/5-1/2 of total length, the axes bearing small caducous bracts at nodes. Flowers 3-5-, mostly 4-merous, apetalous, pedicellate, unisexual and plants dioecious. Sepals valvate, subcoriaceous, connate for 1/4-1/2 of their length. Stamens with filaments subulate, glabrous and anthers transverse-oval, incised at apex and base, in female flowers reduced to about half size and probably sterile. Ovary in male flower absent; Fruit multiple, a follicetum with (2-)3-5 free follicle-like fruitlets, attached to receptacle at base and each dehiscing along the full length of the adaxial suture, the valves boat-shaped, stiff-coriaceous, their margins minutely thickened, the styles, calyx and sometimes stamens persistent. Seeds 1-few per carpel, glabrous, with a small pointed wing at both ends.

Distribution

Asia-Tropical: New Britain: present New Ireland: present Pacific:, Fiji (Fijipresent); Samoa (Samoapresent) Solomon Islands: present Vanuatu: present
6 species ranging from New Britain through the Solomon Islands, Vanuatu, and Fiji to Samoa; in Malesia: a single species in New Britain and New Ireland.

Notes

2. Reference to the occurrence of this genus in Milne Bay Province, Papua New Guinea (Smith 1985) appears to be based on a misidentified specimen of Pullea. 1 Smith (1985) suggested that the plants may sometimes be polygamodioecious, the ‘female’ flowers possibly sometimes having fertile anthers. However, in most specimens, the anthers in female flowers are much reduced compared with those in male flowers.

Citation

A. Gray - in Ann. Sci. Nat. IV Bot. 1855: 176
Engl. - in Nat. Pflanzenfam., ed. 2. 1928: 237
A. Gray, Atlas. 1856: t. 83A
Hutch. - in Gen. Flow. Pl. Dicot. 1967: 8
Hoogland - in Blumea. 1979: f. 2
U.S. Explor. Exped. - in Phan. June 1854: 66
A.C.Sm. - in J. Arnold Arbor. 1952: 139
A.C.Sm. - in Fl. Vit. Nova. 1985: f. 1, 2A.
Seem., Fl. Vit. 1865: t. 17