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Euphorbia revoluta

REVOLUTE SPURGE


Higher Taxonomy
Family: EuphorbiaceaeView DescriptionDichotomous Key
Common Name: SPURGE FAMILY
Habit: Annual to shrub, tree [vine, cactus-like succulent]; monoecious or dioecious; sap clear or milky. Stem: generally branched [fleshy or spiny]. Leaf: generally simple, alternate to whorled, generally stipuled, sessile or petioled; blade entire, toothed, or lobed. Inflorescence: flowers solitary or in terminal or axillary cymes, racemes, spikes, or panicles, or (in Euphorbia) 1° inflorescence a compact, flower-like cyathium with much-reduced flowers enclosed within an involucre of fused bracts, cyathia terminal or axillary, 1 or in cyme-like arrays. Flower: unisexual, +- radial; sepals 0 or 2--6, free or fused; petals generally 0(5); stamens 1--many, free or filaments fused; ovary superior, chambers (1)3(4), styles free or fused, undivided, forked, or variously lobed. Fruit: generally capsule that splits into mericarps that then dehisce, releasing seeds. Seed: 1 per chamber; knob-like appendage sometimes present at attachment scar.
Genera In Family: 217 genera, 6000+ species: +- worldwide especially tropics; some cultivated (Aleurites, tung oil; Euphorbia species; Hevea, rubber; Ricinus). Toxicity: Many species +- highly TOXIC, due primarily to latex, especially if eaten or in contact with skin, eyes. Note: Eremocarpus moved to Croton, Tetracoccus moved to Picrodendraceae for TJM2; Chamaesyce moved to Euphorbia here (key to genera revised by Thomas J. Rosatti).
eFlora Treatment Author: Mark H. Mayfield & Grady L. Webster, except as noted
Scientific Editor: Bruce G. Baldwin.
Genus: EuphorbiaView DescriptionDichotomous Key


Common Name: SPURGE
Habit: Annual to shrub [tree; fleshy, +- cactus-like], glabrous or hairy; sap milky; generally monoecious. Stem: prostrate to erect, generally < 1 m; branches arrayed around main stem(s) in 3-dimensions or 2-ranked, resulting in 2-faced stems with adaxial leaf faces all displayed to top side and abaxial leaf faces to bottom side. Leaf: proximal cauline, alternate or opposite, +- sessile to petioled; distal-most cauline in some species whorled, subtending umbel-like cluster of inflorescence branches, leafy bracts distal to whorled leaves generally opposite (whorled); stipules 0, gland-like, thread-like, or scale-like, free or fused, entire to divided; blade entire or toothed (pinnately lobed), base symmetric or asymmetric. Inflorescence: 1° inflorescence a cyathium, resembling a flower; cyathia 1--many, stalked or sessile, terminal (axillary), in generally leafy-bracted cyme-like arrays; cyathium a compact unit comprising an involucre of 5 fused bracts enclosing 1--many reduced staminate flowers and 1(0) pistillate flower; involucre generally 1--5 mm, bract tips alternate with 1--5 nectary glands (derived from modified stipules of involucre bracts), these transversely crescent-shaped or oblong to +- round, flat to cup-like, entire, toothed, or with 2 horn-like lobes, with or without distal, white to pink or red, flat, petal-like appendages; bractlets within involucre membranous or thread-like, often fringed. Staminate Flower: (1--4)5--many, generally in 5 clusters around pistillate flower (this difficult to observe); calyx 0; each staminate flower a single stamen jointed to tip of a thread-like pedicel; pedicel persistent, stamen deciduous after pollen released. Pistillate Flower: (0)1, central, stalked; calyx 0; ovary chambers 3, styles 3, free or fused at base, undivided or +- deeply forked. Fruit: stalk generally elongating, generally curved, pushing developing fruit from involucre; capsule +- spheric to ovoid or oblong, in ×-section +- round to 3-lobed or -angled. Seed: +- round or +- 3- or 4-angled (flattened) in ×-section, smooth or sculptured; knob-like appendage at attachment scar present or 0.
Etymology: Euphorbus, physician to the King of Mauritania, 1st century Note: Forms monophyletic group with Chamaesyce, included here. Euphorbia serrata L. considered extirpated from California; 2003 report that Euphorbia exigua L. is possibly naturalizing as yet unconfirmed; Euphorbia marginata Pursh occasionally persisting from gardens, but recent records lacking. Euphorbia graminea Jacq. an urban weed. For fruit, seeds, "in ×-section" indicated only if not lobed or angled.
eFlora Treatment Author: David J. Keil, Thomas J. Rosatti, Mark H. Mayfield & Daryl Koutnik
Reference: Horn et al. 2012 Molec Phylogen Evol 63:305--326
Unabridged Reference: Wheeler 1936 Bull S Calif Acad Sci 35:127--147
Euphorbia revoluta Engelm.
NATIVE
Habit: Annual, glabrous. Stem: proximally erect, repeatedly forking, 2-faced, branches diffusely spreading. Leaf: opposite throughout, 2-ranked, subsessile; stipules free, linear; blade 3--26 mm, linear, entire, margin rolled under, base +- symmetric, tip acute to obtuse. Inflorescence: cyathia 1 per node or in small clusters; involucre < 1.5 mm, obconic; glands 4, < 0.5 mm, +- round; petal-like appendage 0 or wider than gland, entire, white. Staminate Flower: 3--8. Pistillate Flower: styles undivided or forked < 1/10. Fruit: slightly < 1.5 mm, spheric, lobed. Seed: 1--1.5 mm, ovoid, 3-angled, transversely 2--3-ridged, white to gray; knob 0.
Ecology: Rocky slopes; Elevation: < 3100 m. Bioregional Distribution: PR, D; Distribution Outside California: to Rocky Mountains, Mexico. Flowering Time: Aug--Sep
Synonyms: Chamaesyce revoluta (Engelm.) Small
Jepson eFlora Author: David J. Keil, Thomas J. Rosatti, Mark H. Mayfield & Daryl Koutnik
Reference: Horn et al. 2012 Molec Phylogen Evol 63:305--326
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)
Listed on CNPS Rare Plant Inventory

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Citation for this treatment: David J. Keil, Thomas J. Rosatti, Mark H. Mayfield & Daryl Koutnik 2013, Euphorbia revoluta, in Jepson Flora Project (eds.) Jepson eFlora, Revision 1, https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=25499, accessed on October 03, 2024.

Citation for the whole project: Jepson Flora Project (eds.) 2024, Jepson eFlora, https://ucjeps.berkeley.edu/eflora/, accessed on October 03, 2024.

Euphorbia revoluta
click for image enlargement
©2012 Keir Morse
Euphorbia revoluta
click for image enlargement
©2012 Keir Morse
Euphorbia revoluta
click for image enlargement
©2012 Keir Morse
Euphorbia revoluta
click for image enlargement
©2012 Keir Morse
Euphorbia revoluta
click for image enlargement
©2012 Keir Morse

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Geographic subdivisions for Euphorbia revoluta:
PR, D
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map of distribution 1

(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurrence).






 

Data provided by the participants of the  Consortium of California Herbaria.

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CCH collections by month Flowering-Fruiting Monthly Counts

Duplicates counted once; synonyms included.
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