Osmoxylon sessiliflorum

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Osmoxylon sessiliflorum


Small tree, up to 18 m, glabrous when mature, or tomentum persistent on the inflorescence. Leaves crowded at the ends of the branches; Inflorescence a terminal compound umbel; Stamens 6-17. Ovary 5-18-celled. Fruit a globose head of drupes;


Asia-Tropical: Maluku (Maluku present); New Guinea present, Halmaheira present
Malesia: throughout New Guinea. Moluccas (Halmaheira), 2 coll.


Unbranched or sparsely branched with crowns of large leaves. The bark is light brown and the wood cream. The inflorescence branches are purple, the flowers red, and the succulent ripe fruits black.
The variation in the numbers of floral parts is considerable. Most specimens have more than 10 stamens and the same number of cells in the ovary, or more. Three gatherings have from 5-7 stamens and cells. These may possibly require to be segregated as a distinct species, but other evidence to support this course is lacking. An even more distinctive gathering has central branches to 3 cm long with the pseudo-fruits on short pedicels (less than 5 mm) and flowers with 17 stamens and 25 cells in the ovary. These characters have not been included in the specific description as this specimen is only very tentatively referred to this species.
This species forms an eastward extension of a complex of species, represented in the Moluccas by 37. O. talaudense, 17. O. soelaense and 18. O. glo- bulare. 'Several similar species occur in the Philippines. They are characterized by dense spherical heads of flowers.
Osmoxylon talaudense resembles some specimens of O. sessiliflorum rather closely, and the difficulty of preserving the characters of these large-leaved plants in an herbarium probably obscures several good diagnostic features. The most reliable character to distinguish these two species is the position of the articulation on the lateral branches of the inflorescence rays. In specimens from the Talaud Is. this is close to the base (below the apex of the central umbellule of pseudo-fruits) and the bracts are persistent, whereas in the New Guinea material it is near (or above) the middle, and is usually marked by two inconspicuous scars which frequently are not opposite. In both species the pseudo-fruits are pedicelled, whereas in the other two Moluccan species the pseudo-fruits are sessile or subsessile forming spherical heads. In O. globu- lare (from Morotai and Halmaheira) the lateral branches are rigid and only slightly flattened with the articulation near the middle and the bracts caducous. In O. soelaense the articulation is much nearer the base, the bracts are persistent, and the branches are broader and much flattened.