Chamaesyce revoluta (Engelm.) Small
Family: Euphorbiaceae
threadstem sandmat,  more...
[Euphorbia revoluta Engelm.]
Chamaesyce revoluta image
Max Licher  
Plant: Erect annual forb 10-20 cm; herbage with milky sap; stems delicate Leaves: cauline, opposite, short-petioled, linear, 1-2 cm long, with revolute margins; tip acute to obtuse INFLORESCENCE: involucre < 1.5 mm, obconic, glabrous; gland < 0.5 mm, round, appendage wider than gland or 0, entire, white Flowers: flowers monoecious borne in cyathia; petaloid appendages white; Staminate flowers 5-10, generally in 5 clusters around pistillate flower, each flower a stamen; Pistillate flower: 1, central, stalked; ovary chambers 3, ovule 1 per chamber, styles 3, divided 1/2 length Fruit: capsule slightly < 1.5 mm, spheric, lobed, glabrous; Seeds 1-1.5 mm, ovoid, 3-angled, white with transverse wrinkles Misc: Rocky slopes; < 3100 m.; Aug-Sep
Wiggins 1964, Jepson 1993, Kearney and Peebles 1969, Allred and Ivey 2012, FNA 2016
Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Annual herb, 5-25 cm tall, from a slender taproot; stems erect, spreading, with very slender branches that fork repeatedly; herbage glabrous. Leaves: Opposite and short-petiolate, located almost entirely at nodes where the stem forks into 2 branches; blades narrowly linear, 1-2 cm long, the margins entire and tightly revolute (curled under), and the midvein impressed on the upper surface of the leaf; stipules narrow and tapering toward the tip, 0.5 mm long. Flowers: Has the highly modified flower structure characteristic of Euphorbias. Structures called cyathia appear to be individual flowers, but are composed of fused-together bracts forming a cup (involucre), with peripheral nectary glands which are often subtended by petal-like bracts called petaloid appendages. Within the cup there is a ring of inconspicuous male flowers, each reduced to a single stamen. Out of the middle protrudes a single, stalked female flower which lacks petals. In E. revoluta, the cyathia (flower structures) are mostly solitary in the nodes near branch tips. Involucres are cone-shaped, 1 mm high, and glabrous, with 4 round glands around the edge, each with a white petaloid appendage which is a bit wider than the gland (or petaloid appendages absent); 5-10 staminate flowers. Fruits: Capsules globose and 3-lobed, to 1.5 mm high, and glabrous; containing 3 ovoid, white to gray seeds, to 1.5 mm long, 3-angled and transversely 2-3-ridged. Ecology: Found on arid hillsides and slopes, from 3,000-6,000 ft (914-1829 m); flowers August-October. Distribution: s CA, s UT, AZ, s CO, NM, TX; south to n MEX. Notes: This species belongs to the Chamaesyce subgenus of Euphorbia. Some treatments, even recent ones, continue to treat Chamaesyce as a separate genus even though molecular evidence places it within Euphorbia. Chamaesyce spp are distinct based on their leaves which are always opposite and and often have asymmetric bases; cyathia (flower structures) in leaf axils, not at branch tips, and usually with petaloid appendages; and stipules present and not gland-like. E revoluta is distinguished by being a delicate, erect, hairless annual with slender, linear leaves. The entire plant often has a reddish/maroon tint, and the stems fork evenly into two branches multiple times, with a pair of leaves and often a single cyathium (flower-like structure) at each fork point. It is wise to make a collection whenever ID to species is needed, as Chamaesyces are difficult to identify in the field, and multiple species of the genus will commonly grow side-by-side. Ethnobotany: Used as a lotion for chafing and sores. Etymology: Euphorbia is named for Euphorbus, Greek physician of Juba II, King of Mauretania; revoluta means rolled backwards, referring to the revolute margins of the meaves. Editor: SBuckley 2010, FSCoburn 2015, AHazelton 2017
Chamaesyce revoluta image
Max Licher  
Chamaesyce revoluta image
Patrick Alexander  
Chamaesyce revoluta image
Chamaesyce revoluta image
Patrick Alexander  
Chamaesyce revoluta image
Patrick Alexander  
Chamaesyce revoluta image
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