Jepson eFlora
Key to families | Table of families and genera

Key to Euphorbia

View taxon page for Euphorbia

1. Proximal leaves alternate, bases generally symmetric

2. Involucre gland appendage petal-like, white; shrub ..... E. misera

2' Involucre gland appendage 0; annual to perennial herb (E. dendroides a shrub)

3. Involucre glands 1–3, less often 4(5), ± cupped

4. Involucre, fruit densely hairy; seed oblong, flattened ..... E. eriantha

4' Involucre, fruit generally glabrous or ± so; seed ellipsoid to oblong or ovoid, not flattened

5. Bracts subtending cyathia each red proximally, green distally; stem glabrous ..... [E. cyathophora]

5' Bracts subtending cyathia each green or ± white proximally or throughout; stem hairy or glabrous

6. Hairs recurved on distal stems, abaxial leaf faces; seed >= 2.2 mm wide, coarsely tubercled ..... [E. davidii] (2)

6' Hairs ± straight, spreading 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 ..... E. terracina

8' Leaf tip rounded, obtuse, or notched

9. Perennial herb; stem densely hairy ..... E. oblongata

9' Annual; stem glabrous or sparsely hairy

10. Whorled inflorescence branches 5; fruit smooth; staminate flowers 8–15 ..... E. helioscopia

10' Whorled inflorescence branches 3; fruit tubercled especially near tip and on lobes; staminate flowers 5–10 ..... E. spathulata

7' Leaf margin generally entire (± entire to minutely crenate)

11. Shrub ..... E. dendroides

11' Annual to perennial herb

12. Annual (biennial)

13. Fruit lobes 2-keeled ..... E. peplus

13' Fruit lobes not keeled ..... E. crenulata

12' Perennial herb

14. Seed smooth

15. Seed ± white; leaves lanceolate ..... [E. rigida]

15' Seed gray to tan or ± brown; leaves linear to (ob)lanceolate ..... E. virgata

14' Seed rarely smooth

16. Seed with ± worm-like papillae (smooth), gray-brown; leaves obovate to ± round ..... [E. myrsinites]

16' Seed generally pitted or surface shallowly net-like, occasionally ± smooth; leaves elliptic to (ob)ovate or spoon-shaped

17. Leaf sessile; stem ascending to erect; gland shortly 2-horned, entire to scalloped between horns ..... E. lurida

17' Leaf ± sessile to short petioled; stem decumbent to erect; gland transversely obovate or fan-shaped, scalloped or incised but not 2-horned ..... E. schizoloba

1' Proximal leaves opposite

18. Leaves 4-ranked on proximal stem, bases symmetric; stems not forked, 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

21. Glands of involucre transversely oblong, without horn-like lobes, white petal-like appendages present; leaves 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; 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)

23. Perennial herb

24. Fruit glabrous ..... E. parishii

24' Fruit hairy ..... E. pediculifera (3)

23' Annual

25. Fruit hairy

26. Involucre < 1 mm, glands << 0.5 mm; staminate flowers 2–5; fruit < 1.5 mm ..... E. micromera (2)

26' Involucre 1.5–2 mm, glands 0.5 mm; staminate flowers 22–25; fruit 2 mm ..... E. pediculifera (3)

25' Fruit glabrous

27. Leaf linear, base ± symmetric; stem proximally erect ..... E. revoluta (2)

27' Leaf oblong, lanceolate to (ob-)ovate to round, base asymmetric; stem prostrate to decumbent

28. Seed ± 2-angled, flattened, smooth; involucre glands transversely obovate ..... E. platysperma

28' Seed 3–4-angled, not flattened, smooth, wrinkled, or transversely ridged; involucre glands round or transversely elliptic

29. Fruit < 1.5 mm; seed 1–1.5 mm; staminate flowers 2–5 ..... E. micromera (2)

29' Fruit 2–2.5 mm; seed 1.5–2 mm; staminate flowers 40–60 ..... E. ocellata

30. Leaf <= 15 mm, lanceolate to ovate; Desert ..... subsp. arenicola

30' Leaf < 10 mm, ovate to sickle-shaped; California Floristic Province (except Peninsular Ranges) ..... subsp. ocellata

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 cyme-like clusters, occasionally 1 per node; 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

34. Perennial herb; fruit 2–2.5 mm; staminate flowers 15–30 ..... E. albomarginata

34' Annual; fruit ± 1.5 mm; staminate flowers 3–8(10) ..... E. serpens

33' Stipules free or fused, but not a wide, membranous scale

35. Perennial herb

36. Fruit, seed 2–2.5 mm; proximal stipules free ..... E. fendleri

36' Fruit, seed 1–1.5 mm; proximal stipules free or fused ..... E. polycarpa (2)

35' Annual

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 entire ..... E. abramsiana (2)

39' Leaf margin toothed, at least toward tip, sometimes finely so

40. Styles simple; involucre gland appendages deeply 3–5-lobed ..... E. hooveri

40' Styles divided; involucre gland appendages entire, scalloped, or shallowly lobed

41. Stem subglabrous to hairy; seed transversely 4–6-ridged ..... E. abramsiana (2)

41' Stem glabrous; seed transversely 3–4-ridged or smooth to wrinkled

42. Seed transversely 3–4-ridged; involucre gland appendage wider than gland ..... E. glyptosperma

42' Seed smooth to wrinkled; involucre gland appendage narrower than gland ..... E. serpyllifolia subsp. serpyllifolia

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 — Sonoran Desert ..... E. arizonica

44' Plant puberulent to finely tomentose, strigose, or short-stiff-hairy with non-jointed hairs; staminate flowers >= 15; involucre urn- or bell-shaped or obconic

45. Seed 3-angled, ridged transversely ..... E. pediculifera (3)

45' Seed 0- or 4-angled (sometimes ± 3-angled in E. jaegeri), smooth to wrinkled or irregularly dimpled or faintly ridged transversely

46. Leaf hairs straight

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

48. Involucre 1–1.5 mm; glands dark red to ± black ..... E. melanadenia

48' Involucre 2–2.5 mm; glands green to yellow or ± red ..... E. vallis-mortae

43' Annual

49. Involucre 1.5–2 mm; fruit 2–2.5 mm; staminate flowers 40–60 ..... E. ocellata subsp. rattanii

49' Involucre < 1.5 mm; fruit 1–2 mm; staminate flowers < 20

50. Involucre gland appendage deeply 3–5-lobed; involucre urn-shaped ..... E. setiloba

50' Involucre gland appendage entire to scalloped; involucre bell-shaped or obconic

51. Fruit 1.5–2 mm; seed wrinkled; involucre gland appendage narrower than gland ..... E. serpyllifolia subsp. hirtula

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

Contact/Feedback

Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
We encourage links to these pages, but the content may not be downloaded for reposting, repackaging, redistributing, or sale in any form, without written permission from The Jepson Herbarium.