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Key to EuphorbiaView taxon page for Euphorbia
(For a list of species in Euphorbia, use the above link.) Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots. 1. Proximal leaves alternate  1. Arranged singly, often spirally, along an axis - e.g., one leaf per node. 2. Occurring in different ranks, appearing to be between, not directly above or below, as 'stamens alternate petals'. , bases generally symmetric 2' Involucre gland appendage 0; annual to perennial  Completing life cycle (germination through death) in more than two years or growing seasons, generally non-woody (at least above ground) to woody; includes perennial herbs as well as subshrubs to trees; the abbreviation 'per' only refers to perennial herb, not to the word 'perennial' alone. herb ( E. dendroides a shrub) 3. Involucre glands 1–3, less often 4(5), ± cupped 4. Involucre, fruit densely hairy; seed oblong  Longer than wide, with nearly parallel sides; wider than linear. , flattened ..... E. eriantha 4' Involucre, fruit generally glabrous or ± so; seed ellipsoid to oblong or ovoid, not flattened 5' Bracts subtending cyathia each green or ± white proximally or throughout; stem hairy or glabrous 6. Hairs recurved  Gradually curved downward or backward. on distal stems, abaxial leaf  Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets). faces; seed >= 2.2 mm wide, coarsely tubercled ..... [E. davidii] (2) 6' Hairs ± straight, spreading  Oriented more or less perpendicularly to the axis of attachment; often, more or less horizontal. on distal stems, abaxial leaf faces; seed <= 2.1 mm wide, finely tubercled ..... [E. dentata] (2) 3' Involucre glands 4(5), ± flat 7. Leaf margin finely to coarsely toothed 8. Leaf tip ± acute  Having a short-tapered, sharp tip, the sides convex or straight and converging at less than a right angle. ..... E. terracina 8' Leaf tip rounded, obtuse  Having a short-tapered, blunt tip or base, the sides convex or straight and converging at more than a right angle. , or notched 9' Annual; stem glabrous or sparsely hairy 10' Whorled inflorescence branches 3; fruit tubercled especially near tip and on lobes  1. A major expansion or bulge, such as on the margin of a leaf, sepal, or petal, or on the surface of an ovary. 2. The free tips of otherwise fused structures, such as sepals or petals; larger than teeth. ; staminate flowers 5–10 ..... E. spathulata 7' Leaf margin generally entire  Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.). (± entire to minutely crenate) 11' Annual to perennial herb 15. Seed ± white; leaves lanceolate  Narrowly elongate, widest in the basal half, often tapered to an acute tip. ..... [E. rigida] 15' Seed gray to tan or ± brown; leaves linear  Elongate, with nearly parallel sides; narrower than elliptic or oblong. to (ob)lanceolate ..... E. virgata 16' Seed generally pitted or surface shallowly net-like, occasionally ± smooth; leaves elliptic  In the shape of a flattened circle or ellipse; wider than linear to (ob)ovate or spoon-shaped 17. Leaf sessile  Without a petiole, peduncle, pedicel, or other kind of stalk. ; stem ascending  Curving or angling upward from base, or about 30-60 degrees less than vertical or away from axis of attachment. to erect  Upright; vertically oriented. ; gland shortly 2-horned, entire to scalloped between horns ..... E. lurida 17' Leaf ± sessile to short petioled; stem decumbent  lying mostly flat on the ground but with tips curving up. to erect; gland transversely obovate or fan-shaped, scalloped or incised but not 2-horned ..... E. schizoloba 1' Proximal leaves opposite  1. Arranged in pairs along an axis - e.g., two leaves per node. 2. Occurring in the same rank, directly above or below, as 'stamens opposite petals'. 3. Located directly across from. 18. Leaves 4-ranked on proximal stem, bases symmetric; stems not forked  Pertaining to a hair or other structure that branches into two parts. , not 2-faced 19. Distal cauline leaves alternate 20. Hairs recurved on distal stems, abaxial leaf faces; seed >= 2.2 mm wide, coarsely tubercled ..... [E. davidii] (2) 20' Hairs ± straight on distal stems, abaxial leaf faces; seed <= 2.1 mm wide, finely tubercled ..... [E. dentata] (2) 19' Distal cauline leaves opposite or whorled  Arranged in groups of three or more at nodes or positions along an axis (e.g., three leaves per node). 21. Glands of involucre  Group of bracts more or less held together as a unit, subtending a flower, fruit (acorn cup), or inflorescence. transversely oblong, without horn-like lobes, white petal-like appendages present; leaves serrate  Having margins with sharp, fine to coarse teeth generally pointing tipward, not outward; margins with such teeth on such primary teeth are doubly serrate. ; 1° inflorescence branches not whorled; fruit 2.5–3.4 mm ..... E. exstipulata var. exstipulata 21' Glands of involucre crescent-shaped, with 2 horn-like lobes, petal-like appendages 0; leaves entire; 1° inflorescence branches whorled; fruit 8–15 mm ..... E. lathyris 18' Leaves 2-ranked, bases generally asymmetric  Not divisible into identical or mirror-image halves. ; stems repeatedly forked, 2-faced 22. Glands of involucre without white to pink or red petal-like appendages (appendages ± 0 on some glands in E. pediculifera) 27' Leaf oblong, lanceolate to (ob-)ovate to round, base asymmetric; stem prostrate  Lying flat on the ground. to decumbent 28' Seed 3–4-angled, not flattened, smooth, wrinkled, or transversely ridged; involucre glands round or transversely elliptic 30. Leaf <= 15 mm, lanceolate to ovate  Egg-shaped (i.e., widest below the middle) in two dimensions (i.e., in one plane), as a leaf. ; D ..... subsp. arenicola 22' Glands of involucre with white to pink or red petal-like appendages (appendages ± 0 on some glands in E. pediculifera) 31. Cyathia generally in dense axillary  Pertaining to or within an axil, especially a leaf axil. cyme-like clusters, occasionally 1 per node  Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise. ; leaves 8–35 mm; stem generally ± erect (decumbent) ..... E. nutans 31' Cyathia 1 per node, occasionally dense on lateral branches or 1 at branch tips; leaves 1–40 mm; stem prostrate to ascending, occasionally erect 32. Fruit glabrous; stem, leaves, involucre generally glabrous (stem, leaves glabrous to hairy in E. abramsiana) 33. Stipules fused into wide, membranous scale  1. Wide, appressed, membranous, epidermal outgrowth (e.g., Cheilanthes covillei) 2. Structure partially or entirely covering an over-wintering bud (bud scale) (e.g., Salix goodingii bud). 3. In gymnosperms, a woody, seed-bearing structure attached to the cone axis (cone scale) (e.g., Abies magnifica). 4. In Asteraceae, a flat, membranous pappus element (e.g., Hymenoxys hoopesii). Leaves or bracts may be scale-like in one or more of the preceding ways. 33' Stipules free or fused, but not a wide, membranous scale 37. Leaves linear, base ± symmetric; stem prostrate to erect 38. Involucre glands 1–4, ovate, appendage narrower than gland; fruit, seed ± 2 mm; seed smooth; stem prostrate to ascending ..... E. parryi 38' Involucre glands ± 4, ± round, appendage wider than gland; fruit, seed <= 1.5 mm; seed transversely ridged; stem proximally erect ..... E. revoluta (2) 37' Leaves elliptic, oblong, lanceolate, ovate, round, or spoon-shaped, base asymmetric; stem prostrate to decumbent 39' Leaf margin toothed, at least toward tip, sometimes finely so 40. Styles simple  Composed of a single part; undivided; unbranched. ; involucre gland appendages deeply 3–5-lobed ..... E. hooveri 40' Styles divided; involucre gland appendages entire, scalloped, or shallowly lobed 41' Stem glabrous; seed transversely 3–4-ridged or smooth to wrinkled 32' Fruit with hairs, at least on lobes; stem, leaves, involucre generally with hairs 43. Perennial herb or shrub 44. Plant soft glandular-hairy with jointed hairs; staminate flowers 5–10; involucre urn-shaped  Widening more or less abruptly at the base and then gradually or abruptly narrowed toward the tip. – DSon ..... E. arizonica 44' Plant puberulent  Minutely hairy. to finely tomentose  Covered with densely interwoven, generally matted hairs. , strigose  With stiff, straight, sharp, appressed hairs. , or short-stiff-hairy with non-jointed hairs; staminate flowers >= 15; involucre urn- or bell-shaped or obconic 45' Seed 0- or 4-angled (sometimes ± 3-angled in E. jaegeri), smooth to wrinkled or irregularly dimpled or faintly ridged transversely 47. Shrub; involucre gland appendage wider than gland, irregularly divided from halfway to ± base into 4–8 ± triangular to awl-shaped segments ..... E. jaegeri 47' Perennial herb; involucre gland appendage narrower to wider than gland, entire to scalloped ..... E. polycarpa (2) 46' Leaf hairs not straight 49' Involucre < 1.5 mm; fruit 1–2 mm; staminate flowers < 20 50' Involucre gland appendage entire to scalloped; involucre bell-shaped or obconic 51' Fruit <= 1.5 mm; seed transversely ridged or wrinkled; involucre gland appendage as wide as to wider than gland 52. Seeds transversely wrinkled; fruit evenly strigose; involucre gland appendage as wide as gland ..... E. maculata 52' Seeds transversely ridged; fruit hairy only on lobes; involucre gland appendage as wide as to wider than gland ..... E. prostrata
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Citation for the whole project: Jepson Flora Project (eds.) . Jepson eFlora, https://ucjeps.berkeley.edu/eflora/ [accessed on ]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on .
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