Euphorbia 



EUPHORBIACEAE 



Euphorbia 



and 1 pistillate fl. in perianth-like gland-bearing involucres (cyathia) which often occur 

 in clusters; staminate fls. of single stamens, and pistillate fl. a 3-celled ovary, both 

 lacking floral envelopes: fr. a capsule. About 600 species, in all parts of the world; 

 25 in China. (Named after Euphorbus, a Greek physician to King Juba of Numidia.) 



E. milii 



Key to the Species 



a. Infl. not subtended by conspicuous bracts, or by colored lvs.: seeds 



oblong-tetragonous (Sect. Chamaesyce). 



Capsules glabrous: glands of the cyathium sessile or nearly so, 



oblong, bordered on the outside by a narrow white petal-like 



appendage with a 3-lobed or sub-entire margin: seeds brown, 



not wrinkled, finely granular, with mottled white-pustulate 



coat: delicate prostrate annual 1. E. humifusa 



Capsules pubescent: glands of the cyathium stipitate, without 

 petal-like appendages: seeds with 4-6 shallow transverse 

 wrinkles, not coated. 

 Cyathia on short axillary lfy. brts.: delicate prostrate annual: 



lvs. elliptic, oblong or ovate-lanceolate, 3-10 mm. long 2. E. thymifolia 



Cyathia in dense axillary terminal leafless glomerules: erect or 

 decumbent annual: lvs. ovate to narrowly lanceolate, 10- 



40 mm. long 3. E. hirta 



aa. Infl. subtended by conspicuous bracts, or by colored lvs. 

 b. Infl. subtended by white, yellow or red bracts or lvs. 



c. Plant a spiny shrub: brs. not strongly angled: cyathia 



closely subtended by two broadly ovate bright red 



bracts about 1cm. across. (Sect. Euphorbium) 4. 



cc. Plants not spiny, herbs or shrubs: the upper leaves red, 



pink or white, or blotched with red and white, or 



margined with white. 



Upper lvs. margined with white; a stout annual: glands 



of the cyathium with white petal-like appendages: 



capsule usually pubescent; seeds ovoid-globose, terete, 



gray, reticulate-tuberculate, 4 mm. long (Sect. 



Petaloma) 5. E. marginata 



Upper lvs. red, pink or white, or blotched red and 



white: shrubs or herbs: glands of the cyathium 



without petal-like appendages: capsules glabrous or 



pubescent (Sect. Poinsetlia) 



Upper lvs. uniformly red, pink or white, ovate-elliptical 



to lanceolate, 8-15 cm. long; a winter-fig. shiub, 



0.5-3 m. high: cyathia with a single large yellow 



gland on one side 6. E. pidcherrvma 



Upper lvs. red at the base or blotched with red and 

 white, variable in size, ovate, fiddle-shaped or linear; 

 annual or biennial, 0.3-1 m. high: cyathia with one 

 or two glands: seeds oblong-ovoid 3-4 mm. long, 



transversely wrinkled and tuberculate 7. 



bb. Infl. umbellate, subtended by a whorl of 4-6 oblong, spatulate, 

 lanceolate or linear leaf -like herbaceous bracts; 

 mostly erect stout herbs: glands of the cyathium 

 without petal-like appendages (Sect. Tithy mains). 



d. Lvs. and bracts of the main umbel all obovate and broadly 



rounded or retuse at the apex, margins finely serrate; 



E. heterophylla 



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