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trans-Pecos croton

woolly croton

Habit Shrubs, 1–4 dm, dioecious. Herbs, annual, 5–15 dm, monoecious; stems, leaves, and buds whitish-hairy when young, becoming glabrate.
Stems

much branched proximally, coarsely stellate-tomentose.

well branched distally, stellate-hairy.

Leaves

not clustered;

stipules each 1 glandular papilla, 0.1 mm;

petiole 0.1–0.4(–0.6) cm, 1/10–1/5 blade length, glands absent at apex;

blade ovate to elliptic-ovate, 1–3(–4.5) × 0.5–1.5(–2) cm, base usually rounded to obtuse, rarely acute, margins entire, apex acute or rounded, abaxial surface pale green to pale yellow, stellate-tomentose, adaxial surface darker green, stellate-tomentose.

not clustered;

stipules linear, 2–7 mm;

petiole 0.5–5 cm, glands absent at apex;

blade ovate-lanceolate, 3–10 × 1–5 cm, base cordate to rounded, margins entire, apex acute, abaxial surface pale green, not appearing brown-dotted, no stellate hairs with brown centers, adaxial surface darker green, both stellate-hairy.

Inflorescences

unisexual;

staminate racemes, 1–3.3 cm, flowers 1–8;

pistillate congested racemes, 0.1–0.3 cm, flowers 1–3.

bisexual, racemes, 2–4 cm, staminate flowers 3–10, pistillate flowers 4–8.

Pedicels

staminate 1 mm, pistillate 0–0.5 mm.

staminate 2–4 mm, pistillate 1–2 mm.

Staminate flowers

sepals (4–)5, 2 mm, abaxial surface stellate-hairy;

petals (4–)5, narrowly oblanceolate, 1.8–2 mm, abaxial surface nearly glabrous;

stamens 9–12.

sepals (4–)5, 1–2 mm, abaxial surface stellate-hairy;

petals 5, linear-oblong-lanceolate, 1–1.5 mm, abaxial surface stellate-hairy;

stamens 9–12.

Pistillate flowers

sepals 5, equal, 1 mm, margins entire, apex straight to slightly incurved, abaxial surface stellate-hairy;

petals 0 or rudimentary;

ovary 3-locular;

styles 3, 1.5–2 mm, 2-fid to base, terminal segments 6.

sepals 7–8, subequal, 3–6 mm, margins entire, apex straight to slightly incurved, abaxial surface whitish appressed-tomentose;

petals 0;

ovary 3-locular;

styles 3, 3–4 mm, 4-fid, terminal segments 12.

Capsules

4–5 × 5.5–6 mm, smooth;

columella apex with 3 rounded, inflated lobes.

6–8 × 6–7 mm, smooth;

columella tipped with 3-pronged grappling hooklike appendage.

Seeds

3.6–4.7 × 2.8–3.4 mm, shiny.

4–5 × 2–2.5 mm, shiny.

Croton sancti-lazari

Croton heptalon

Phenology Flowering Oct–Nov. Flowering May–Dec.
Habitat Rocky hillsides. Beaches, coastal dunes, roadsides.
Elevation 900–1200 m. (3000–3900 ft.) 0–50 m. (0–200 ft.)
Distribution
from FNA
TX; Mexico (Chihuahua, Coahuila)
[BONAP county map]
from FNA
TX; e Mexico
[BONAP county map]
Discussion

Croton sancti-lazari in the flora area grows only in Brewster and Presidio counties.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Morphological differences among Croton heptalon and its multifid-styled relatives in sect. Heptallon, especially C. capitatus and C. lindheimeri, can be quite subtle. In general, C. heptalon can be distinguished from C. capitatus by its more elongate pistillate part of the inflorescence, non-recurving sepal tips in the pistillate flowers, and more cordate leaf bases on larger basal leaves. Whitish pubescence on its young growth and styles that branch once into four terminal segments distinguish C. heptalon from C. lindheimeri.

Croton muelleri J. M. Coulter, which is an illegitimate name, pertains here.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 12, p. 222. FNA vol. 12, p. 217.
Parent taxa Euphorbiaceae > Croton Euphorbiaceae > Croton
Sibling taxa
C. alabamensis, C. argenteus, C. argyranthemus, C. californicus, C. capitatus, C. ciliatoglandulifer, C. cortesianus, C. coryi, C. dioicus, C. elliottii, C. fruticulosus, C. glandulosus, C. heptalon, C. humilis, C. incanus, C. leucophyllus, C. lindheimeri, C. lindheimerianus, C. linearis, C. michauxii, C. monanthogynus, C. parksii, C. pottsii, C. punctatus, C. setigerus, C. soliman, C. sonorae, C. suaveolens, C. texensis, C. wigginsii
C. alabamensis, C. argenteus, C. argyranthemus, C. californicus, C. capitatus, C. ciliatoglandulifer, C. cortesianus, C. coryi, C. dioicus, C. elliottii, C. fruticulosus, C. glandulosus, C. humilis, C. incanus, C. leucophyllus, C. lindheimeri, C. lindheimerianus, C. linearis, C. michauxii, C. monanthogynus, C. parksii, C. pottsii, C. punctatus, C. sancti-lazari, C. setigerus, C. soliman, C. sonorae, C. suaveolens, C. texensis, C. wigginsii
Synonyms C. abruptus Oxydectes heptalon, C. albinoides, C. capitatus var. albinoides, C. engelmannii var. albinoides, C. muelleri var. albinoides, Heptallon aromaticum
Name authority Croizat: J. Arnold Arbor. 26: 185. (1945) (Kuntze) B. W. van Ee & P. E. Berry: Syst. Bot. 35: 159. (2010)
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