Bristlecup Sandmat

Euphorbia chaetocalyx var. chaetocalyx

Description 2

Plants glabrous clumping or rhizomatous perennials, erect to ascending; plants small, less than 15 cm tall and across; usually taller than wide. Many slender stems; largest internodes less than 1 mm in diameter. Stipules united into a narrow appendage or divided, especially divided closer to cyathia. Leaves linear-lanceolate (to lanceolate-ovate in some), sometimes ovate near the base of some plants. Appendages tapering to a blunt point, longer than wide and longer than the glands are wide; often there is one cyathium closer to the base that is twice as large as others, has many more staminate flowers, and has wide appendages that are serrated or lobed. Involucres usually red.

Habitat and Distribution 2

Only known on the Llano from one location on the southwestern edge (west of Notrees, Ector Co.; specimens at SRSC). This species grows in rocky limestone.

Comments 2

This species and E. fendleri occasionally have whorled leaves. One specimen at the Notrees locality has consistently whorled leaves on several plants. It is not known if this characteristic is populational or simply anomalous (as in all E. fendleri specimens and plants seen).

Euphorbia chaetocalyx is very similar to E. fendleri and requires some further study to differentiate between the two throughout the entire range of the two species. On the Llano, the two can easily be distinguished by the following characteristics:

Euphorbia chaetocalyx: Habit erect or ascending usually clumping; leaves linear-lanceolate at least toward the apices of stems; appendages present, triangular.
Euphorbia fendleri: Habit prostrate, rarely ascending in shade, rhizomatous; leaves ovate, typically short lanceolate toward the apices of stems; appendages usually absent, if present, lunate.

Sources and Credits

  1. (c) Nathan Taylor, all rights reserved, uploaded by Nathan Taylor
  2. (c) Nathan Taylor, some rights reserved (CC BY-SA)

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