Small to large monoecious or polygamo-monoecious trees, often buttressed. Bark smooth or finely fissured, often conspicuously warty lenticellate. Leaves entire 3r not, 3-nerved at base, semideciduous or persistent. Stipules thick and tough, peltately attached or free and scarious, caducous. Inflorescenses ♂, ⚥, or ♂⚥, branched racemes or panicles, few- to many-flowered, axillary or subterminal on the new shoot; Seed:
Asia-Tropical: Old and New World tropics: present
About 50-60 spp., widely distributed in tropical and temperate regions of the world, the majority of species (30-40) in the Old and New World tropics, throughout Malesia (9 spp.). , .
Except for C.paniculata the stamens of the pistillate flowers are well-developed and functional. In the male or staminate flowers the pistillode is rudimentary or completely absent in C. tetrandra, C. timorensis, and C. rubrovenia. In the other species the pistillode is present and relatively rather well-developed though non-functional.
The chromosome numbers reported are: n = 10 (2n = 20) (C. australis var. eriocarpa, C. inguana, C. laevigata, C. occidentalis, C. sinensis, and C. timorensis (under C. cinnamomea)); 2n = 22 (C. spinosa); 2n = 28 (C. occidentalis); 2n = 40 (C australis and C. tupalangi).
According to SAX l.c there seems to be at least in C. occidentalis a high degree of pollen sterility and a high incidence of meiotic irregularity. This may be one of the causes why in Celtis there is a very high percentage of barren seeds production, even among tropical species.
No detailed study on the microsporogenesis, megasporogenesis and embryogenesis of Celtis species has ever been carried out. In Malesia the solitary ovule is bitegmic, anatropous and inserted just below the apex of the locule. After fertilization both integuments develop into thin membranous seed coats with a broad, dark-coloured, more or less circular chalaza. The endocarp becomes woody and very hard and impregnated by mineral deposits. It is persistent and becomes variously sculptured (ridged, pitted, or nearly smooth). The embryo is strongly curved with the hypocotyle superior and ascending, situated in between or nearly enclosed by the broad, thick, foliaceous cotyledons. The cotyledonar lobes are somewhat unequal in thickness, and they are either induplicate or variously folded. Endosperm is very scanty to absent and either gelatinous or oily. Especially in C. particulata and C. tetrandra, at least 70-80% of the fruits produced are barren. Though the fruits are developed normally, the embryo fails to grow and becomes shrivelled. As a result the fruits are empty.
J. J. SMITH - in K. & V., Bijdr. 12. 1910: 639
Bl. - in Mus. Bot. 1856: 66
LINNÉ - in Sp. Pl. 1753: 1043
B. & H. - in Gen. Pl. 1880: 354
LEROY - in FL Madag. et Com. Fam. 1952: 3
MIQ. - in Fl. Ind. Bat. 1859: 219
Bl. - in Mus. Bot. 1856: 70
BERNARD - in Bull. Herb. Boiss. 1905: maps 9-15
PLANCH - in DC., Prod. 17. 1873: 168
ENGL - in E. & P., Nat. Pfl. Fam., ed. 3, 1. 1888: 63
PLANCH. - in Ann. Sc. Nat. 1848: 262
ELIAS - in J. Arn. Arb. 1970: 32
HUTCH. - in Gen. Fl. Pl. 1967: 147
MIQ. - in Fl. Ind. Bat. 1859: 220
SOEPADMO - in Whitmore, Tree FL Mai. 2. 1973: 414
POLHILL - in Kew Bull. 1964: 139