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Neotropical Euphorbiaceae s.l.
Sebastiania
SUMMARY
Trees or shrubs, monoecious. Exudate present, white. Unarmed*. Glabrous throughout. Stipules free*, simple or compound, entire or lobed, entire or toothed, not spine-like*, not leaf-like*, without glands. Leaves distributed evenly along stem, alternate, simple, unlobed, base symmetrical, margin toothed, blade not pellucid-punctate, leaf glands present, strictly marginal; venation pinnate or rarely with 3 – 7 strong veins from base; domatia absent*; stipel-like structures absent*. Petiole present, without swellings or bends at base or apex*, without glands. Inflorescence with axis, terminal; bracts glandular or not, initially covering floral buds, not leaf-like*, green; pedicels absent or present, not articulated*. Male flowers: sepals 3; partially fused, greenish; petals 0; disc 0; stamens 3, free; anther without conspicuous modification, thecae extrorse in bud; pistillode absent. Female flowers: sepals 3; partially fused, greenish; petals 0; disc 0; ovary locules 3, ovules per locule 1; styles 3, free* or partially fused*, style entire, ultimate divisions per locule 1 or 3, styles or stigmas not flat*, surface smooth*; staminodes absent. Fruit dehiscent, not sculptured (echinate in a single species of dubious affinity) or spiny or bristly, greenish to brown; seed without appendage or covering or with appendage at one end or partial covering, carunculate or not fleshy, , without appendages or membranous layer*; embryo flat, not minute, cotyledons leaf-like.
An asterisk * indicates a state has been assumed but not yet confirmed.
Radcliffe-Smith (2001): 25 spp. or less; World Checklist: about 75 spp.
For this genus there is conflict between the genus description and the World Checklist. The description follows Esser’s modern concept in Radcliffe-Smith (2001), recognizing Sebastiania as group of only 25 species or less, with many of the species traditionally belonging to the genus being treated instead as Gymnanthes. The formal transfer of the species from Sebastiania to Gymnanthes is still pending, hence the conflict with the World Checklist. In practical terms this means that where it is important to use technically correct names for species, many species that almost certainly do not belong to Sebastiania must still be called Sebastiania. A similar conflict exists between Pleradenophora and Sebastiania (see under Pleradenophora). For further discussion see Esser, H.-J., Fátima de Araújo, M.F. & Alves, M. (2010). A new species of Gymnanthes (Euphorbiaceae) from northeastern Brazil. Willdenowia 40: 345-349.
With thanks to Hans-Joachim Esser (Botanische Staatssammlung München) for help with this genus.