Euphorbiaceae

Abstract

Monoecious or dioecious trees, shrubs, or herbs, sometimes succulent or scandent; stems with or without laticifers; indumentum simple, malphighiaceous, stellate, or lepidote, sometimes glandular or 0. Leaves alternate, spiral or distichous, less commonly opposite or whorled; leaf blades simple to palmately lobed or compound, pinnately to palmately nerved, sometimes with basal, laminar, or marginal glands; stipules persistent or deciduous, sometimes reduced or 0. Inflorescences axillary or terminal, sometimes cauliflorous, thyrsoid, paniculate dichasial, glomerulate or synanthial, or flowers solitary; bracts sometimes colored, glandular, or hypertrophied. Flowers unisexual, usually actinomorphic; perianth segments distinct or connate, imbricate to valvate, rarely obsolete or suppressed; sepals (1–)3–6(−10), entire or lobed, sometimes glandular, the pistillate persistent or deciduous in fruit; petals + or 0, greenish to white, yellow, pink, or red; disk + or 0, extrastaminal or less commonly interstaminal, entire to toothed, lobed, or dissected; stamens (1–)3–50(−400), filaments distinct or connate; anthers mostly 2-locular, dehiscing longitudinally or laterally, extrorse or less commonly introrse; gynoecium syncarpous, ovary (1)2–5(−20)-locular; placentation axile (basal); ovules 1 or 2 per locule, anatropous or hemitropous, epitropous, usually inserted beneath an obturator. Fruits mostly schizocarpic, splitting from the columella, commonly explosively dehiscent, mesocarp often separating from endocarp, sometimes baccate or drupaceous. Seeds often carunculate; seed coat mostly exotegmic; endosperm copious, often fleshy, or 0, sometimes oily; embryo straight, curved or plicate.

By the end of 2004 Dr. Grady L. Webster sent me a far advanced version of his treatment of the Euphorbiaceae for this book series and, in June 2005 a few months before his death (Oct. 27, 2005), I received an additional document from him dealing with a review of suprageneric and generic taxa in the family. That year, I could not immediately take care of these documents because I was busy with other volumes of this series. In 2008, through the courtesy of Drs. K.J. Wurdack and P.E. Berry, I received what I thought to be further updated documents left by Grady at the time of his death in his laboratory; contrary to my expectation, however, these did not differ from those supplied earlier by Grady himself. Although the author had made perusal of many taxonomic revisions and publications on pollen morphology and seed anatomy, it was evident that the manuscript needed substantial revision in the light of more recent publications in molecular systematics accrued before and after Grady's death. Regrettably, Dr. Wurdack, the born heir of Grady, did not wish to revise the manuscript so that this task fell onto me, in an effort to not loose Grady's work spanning several years. The paper thus contains many changes introduced by me without being able to secure the author's formal approval, but these were essential for this paper to reflect the high standard that distinguished Dr. Webster's scientific production. Whereas the molecular-cladistic papers on the euphorbs in the widest sense, mainly those by Wurdack and Berry and their co-authors, were of greatest value for me in this task, I must emphasise that the main objective of this series is to give baseline information, whereas further elaboration of a cladistic classification of the family would have been beyond my desire and capacity.

My thanks go to Drs. K.J. Wurdack and P.E. Berry for showing me the manuscripts left by the late Dr. Webster. Prof. W.S. Armbruster is warmly thanked for going through parts of the manuscript lying within his interest and for updating the section on reproductive biology. I am also most grateful to Dr. R. Secco for his comments on Amazonian euphorbs, and to Dr. V.W. Steinmann for advice on subtribe Euphorbiinae.

K. Kubitzki