Horsfieldia

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Horsfieldia

Description

Shrubs or usually trees, dioecious. Leaves sometimes dispersed, brittle when dry, lower surface not pale, papillose only in H. iryaghedhi, dots present or absent; Inflorescences (on older wood in H. sabulosa) paniculate, usually branched several times; Flowers small, mostly short-pedicelled, at base articulated or not, bracteole absent. Fruits globose or ellipsoid, 1-8 cm long, pericarp leathery or somewhat fleshy, with or without lenticel-like tubercles, glabrous or pubescent, perianth sometimes persistent;

Distribution

Asia-Temperate:, Hainan (Hainanpresent) Asia-Tropical:, Lesser Sunda Is.absent Caroline Islands: present Kwangsi: present N Australia: present Solomon Islands: present from Sri Lanka through NE India to S China: present
More than 100 species, ranging from Sri Lanka through NE India to S China (Kwangsi, Hainan) and through Malesia and theCaroline Islands east to the Solomon Islands and N Australia. The genus is absent in the Lesser Sunda Islands and 8 species occur exclusively outside the Malesian area. Except for a few widely distributed species, e.g., H. amygdalina (extra-Malesian), H. glabra, H. irya, H. laevigata, H. tuberculata, most species have a limited distribution.
(see p. 4).

Distinct centres of species development are New Guinea and Borneo, and to a lesser extent Sumatra and Peninsular Malaysia. Three sections have been recognized here, and they occupy largely exclusive areas. Section Horsfieldia, with only H. iryaghedhi, is confined to Sri Lanka. Section Irya (with c. 40 species) is, except for the widespread H. irya, confined to East Malesia, the Solomons and N Australia. Section Pyrrhosa occurs west of Wallace's Line. In distribution, sections Irya and Pyrrhosa overlap for a narrow area in the Philippines and Sulawesi. They are morphologically segregated mainly by a different number of perianth lobes. Some species with the aberrant number of 3 lobes occur in section Irya: H. angularis, H. olens, andiF/. sepikensis. In section Pyrrhosa the deviating number of 2 lobes is found in H. longiflora, H. thorelii, and H. amygdali- na, partly (these three species are extra-Malesian), and H. crassifolia and H. sterilis. For a further explanation, see De Wilde ('1984; 1985).

Taxonomy

There is a large morphological diversity in the flowers of the genus Horsfieldia. Schematic drawings of the androecia of most species have been depicted here on pages 58-61 as , , . Three sections can be recognized and are supposedly of unequal taxonomic weight but with significant different ranges of distribution (see above): 1) sect. Horsfieldia, containing one single species, the type species of the genus, rather deviating from all other species, 2) sect. Irya, containing most species with predominantly a 2-lobed perianth, and 3) sect. Pyrrhosa, most of its species with predominantly a 3- or 4-lobed perianth. The descriptions of the three sections have been given here separately and are not included in the treatment of the species, which are all listed alphabetically.

Notes

Besides a general key to the species (1), based on male flowering specimens, five separate regional keys (2- 6) are given, based on female flowering and fruiting specimens and with emphasis on vegetative characters and partly on distribution.

In species with a laterally compressed androecium (generally in flowers with a 2-lobed perianth) the shape and size of the androecium, as given in the keys and descriptions, always concern the outline as seen laterally.

Citation

Warb., Mon. Myrist. 1897: 130,262
J. Sinclair - in Gard. Bull. Sing. 1974
W. J. de Wilde - in Gard. Bull. Sing. '1985’, 1986
J. Sinclair - in Gard. Bull. Sing. 1958: 368
Willd. - in Blumea. 1996
J. Sinclair - in Gard. Bull. Sing. 1975
W. J. de Wilde - in Gard. Bull. Sing. 1985
Willd. - in Tree Fl. Sabah & Sarawak. 2000: 352
Willd. - in Blumea. 1987
W. J. de Wilde - in Gard. Bull. Sing. '1984', 1985
Pers. - in Symb. 1807: 635
W. J. de Wilde - in Gard. Bull. Sing. 1986