Euphorbia chaetocalyx

(Boissier) Tidestrom

Proc. Biol. Soc. Wash. 48: 40. 1935.

Common names: Bristlecup sandmat
Basionym: Euphorbia fendleri var. chaetocalyx Boissier in A. P. de Candolle and A. L. P. P. de Candolle Prodr. 15(2): 39. 1862
Synonyms: Chamaesyce chaetocalyx (Boissier) Wooton & Standley
Treatment appears in FNA Volume 12. Treatment on page 263. Mentioned on page 257, 264, 282, 267, 270, 282.

Herbs, perennial, with woody, thickened taproot. Stems usually erect, rarely slightly decumbent, often densely clustered from top of woody crown, 3–15 cm, glabrous. Leaves opposite; stipules distinct, narrowly linear, usually entire, 0.5–1 mm, glabrous; petiole 0.5–1 mm, glabrous; blade ovate to lanceolate or oblong or linear-lanceolate, 3–11 × 0.8–3 (–5) mm, base slightly asymmetric, short-tapered, occasionally one side slightly rounded, margins entire, apex acute or short-acuminate, surfaces glabrous; only midvein conspicuous. Cyathia solitary at distal nodes; peduncle 0.8–1.3 mm. Involucre campanulate to turbinate, 0.8–1.4 × 0.8–1 mm, glabrous; glands 4, yellowbrown to reddish, concave or convex, elliptic or oval, 0.2–0.4 × 0.4–0.6 mm; appendages absent or white, lanceolate-deltate to straplike, 0.2–1.1 × 0.2–0.9 mm, distal margin entire, crenate, or deeply cleft or divided. Staminate flowers 25–35. Pistillate flowers: ovary glabrous; styles 0.3–0.4 mm, 2-fid 1/2 length. Capsules depressed-ovoid to depressed-globose, 1.7–2.1 × 1.6–2.4 mm, glabrous; columella 1.2–1.8 mm. Seeds white, ovoid-pyramidal, prominently 4-angled in cross-section, 1.6–2 × 1–1.2 mm, smooth to slightly wrinkled.

Distribution

V12 102-distribution-map.jpg

Ariz., N.Mex., Tex., n Mexico

Discussion

Varieties 2 (2 in the flora).

Euphorbia chaetocalyx is similar to E. fendleri but can generally be distinguished from that species by its narrow, acute leaves and ± erect stems. Some authors have used the presence or absence and shape of the involucral gland appendages to help separate E. chaetocalyx from E. fendleri, but those characters appear highly variable and of little taxonomic utility. Some individuals from western Texas (Culberson and El Paso counties) and southern New Mexico appear intermediate with E. fendleri. The specific epithet of E. chaetocalyx refers to the bristly perianthlike segments that subtend the ovary, but these structures are found intermittently in both E. chaetocalyx and E. fendleri.

Selected References

None.

Key

1 Leaf blades ovate to lanceolate or oblong- or linear-lanceolate; involucral gland appendages absent or lanceolate-deltate, entire, crenate, or deeply cleft; widely distributed in Arizona, New Mexico, w Texas. Euphorbia chaetocalyx var. chaetocalyx
1 Leaf blades narrowly-ovate to linear-lanceolate; involucral gland appendages straplike, divided into 3–5 linear segments; cliffs and rocks of Boquillas Canyon, sw Texas. Euphorbia chaetocalyx var. triligulata

"connate" is not a number. "distinct" is not a number."/2" is not declared as a valid unit of measurement for this property.

... more about "Euphorbia chaetocalyx"
short-acuminate;acute +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.11 cm1.1 mm <br />0.0011 m <br />) +
lanceolate-deltate +  and straplike +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.09 cm0.9 mm <br />9.0e-4 m <br />) +
Victor W. Steinmann +, Jeffery J. Morawetz +, Paul E. Berry +, Jess A. Peirson +  and Ya Yang +
(Boissier) Tidestrom +
short-tapered +
Euphorbia fendleri var. chaetocalyx +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (1.1 cm11 mm <br />0.011 m <br />) +
ovate;lanceolate or oblong or linear-lanceolate +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
0.17 cm1.7 mm <br />0.0017 m <br /> (0.21 cm2.1 mm <br />0.0021 m <br />) +
depressed-ovoid +  and depressed-globose +
0.16 cm1.6 mm <br />0.0016 m <br /> (0.24 cm2.4 mm <br />0.0024 m <br />) +
0.12 cm1.2 mm <br />0.0012 m <br /> (0.18 cm1.8 mm <br />0.0018 m <br />) +
Bristlecup sandmat +
divided +, cleft +, crenate +  and entire +
Ariz. +, N.Mex. +, Tex. +  and n Mexico +
pistillate +  and staminate +
yellowbrown +  and reddish +
0.2mm;0.4mm +
subtending +
oval +, elliptic +, convex +  and concave +
0.4mm +  and 0.6mm +
axillary +  and terminal +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.14 cm1.4 mm <br />0.0014 m <br />) +
campanulate +  and turbinate +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
caducous +, deciduous +  and persistent +
bractlike +
palmate +  and pinnate +
toothed +  and entire +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.13 cm1.3 mm <br />0.0013 m <br />) +
connate;distinct +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
Proc. Biol. Soc. Wash. +
0.16 cm1.6 mm <br />0.0016 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
smooth +  and slightly wrinkled +
4-angled +  and ovoid-pyramidal +
0.1 cm1 mm <br />0.001 m <br /> (0.12 cm1.2 mm <br />0.0012 m <br />) +
rounded +
free +, connate +  and distinct +
flattened +  and terete +
3 cm30 mm <br />0.03 m <br /> (15 cm150 mm <br />0.15 m <br />) +
interpetiolar +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
connate +  and distinct +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (?) +  and 0.04 cm0.4 mm <br />4.0e-4 m <br /> (?) +
Chamaesyce chaetocalyx +
Euphorbia chaetocalyx +
Euphorbia sect. Anisophyllum +
species +
axillary +  and terminal +
10 +, 9 +, 8 +, 7 +  and 6 +