Flora of North America species comparison

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Croton heptalon

Croton lindheimerianus

woolly croton

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

well branched distally, stellate-hairy.

dichotomously branched, densely stellate-tomentose.
Leaves

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.

sometimes clustered near inflorescences;

stipules rudimentary;

petiole 0.5–3 cm, glands absent at apex;

blade lanceolate to suborbiculate, 1–5(–8) × 0.8–2.8(–3.5) cm, base rounded, margins entire, apex rounded to acute, abaxial surface pale green, stellate-hairy, adaxial surface darker green, sparsely stellate-hairy.
Inflorescences

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

bisexual, racemes, 1–3 cm, not appearing brown-dotted, no stellate hairs with brown centers, staminate flowers 3–8, pistillate flowers 1–3.
Pedicels

staminate 2–4 mm, pistillate 1–2 mm.

staminate 2–3 mm, pistillate 1–5(–15) mm.
Staminate flowers

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.

sepals (4–)5, 1.5–2 mm, abaxial surface stellate-hairy;

petals 5, linear-oblong-lanceolate, 1–1.5 mm, abaxial surface glabrous except margins villous;

stamens 7–9(–12).
Pistillate flowers

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.

sepals 5–6, equal, 3 mm, margins entire, apex incurved, abaxial surface stellate-hairy;

petals 0;

ovary 3-locular;

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

6–8 × 6–7 mm, smooth;

columella tipped with 3-pronged grappling hooklike appendage.

4–5 × 4–4.5 mm, smooth;

columella apex with 3 sharp projections.
Seeds

4–5 × 2–2.5 mm, shiny.

3.2–3.6 × 1.5 mm, shiny.

Croton heptalon

Croton lindheimerianus
Phenology Flowering May–Dec.
Habitat Beaches, coastal dunes, roadsides.
Elevation 0–50 m. (0–200 ft.)
Distribution
from FNA
TX; e Mexico
[BONAP county map]
from FNA
AR; AZ; IL; IN; KS; LA; MO; NC; NM; OK; SC; TX; n Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

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.)

Varieties 2 (2 in the flora).

Croton lindheimerianus is one of the bifid-styled species in sect. Heptallon.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Leaf blades suborbiculate, length mostly less than 2 times width, apex rounded to broadly acute; plants densely velvety appressed-tomentose; pedicels, at least some, recurved in fruit.
var. lindheimerianus
1. Leaf blades lanceolate, length mostly more than 2 times width, apex acute; plants roughly tomentose; pedicels erect in fruit.
var. tharpii
Source FNA vol. 12, p. 217. FNA vol. 12, p. 219.
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. 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
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. 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
Subordinate taxa
C. lindheimerianus var. lindheimerianus, C. lindheimerianus var. tharpii
Synonyms Oxydectes heptalon, C. albinoides, C. capitatus var. albinoides, C. engelmannii var. albinoides, C. muelleri var. albinoides, Heptallon aromaticum
Name authority (Kuntze) B. W. van Ee & P. E. Berry: Syst. Bot. 35: 159. (2010) Scheele: Linnaea 25: 580. (1852)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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