Flora of North America species comparison

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Stillingia

Stillingia spinulosa

toothleaf

annual toothleaf, broad-leaf stillingia
Habit Herbs, subshrubs, or shrubs [trees], annual or perennial, monoecious; hairs absent [rarely glandular]; latex white. Herbs, annual or perennial, with taproot.
Stems

fascicled, decumbent to erect, branching distally, 0.5–3 dm.
Leaves

deciduous, alternate, opposite, or subopposite [whorled], simple;

stipules absent or present, persistent;

petiole absent or present, glands absent [small sessile gland at apex];

blade unlobed, margins entire, dentate, crenate, serrulate, or spinulose-dentate, laminar glands absent;

venation pinnate.

opposite or subopposite;

stipules absent;

petiole absent;

blade elliptic to elliptic-spatulate, 1.5–4(–4.5) × 0.5–1.4(–1.8) cm, base narrowly cuneate, margins prominently spinulose-dentate, teeth without prominent blackened tips, not incurved, apex acuminate;

midvein and secondary veins prominent.
Inflorescences

bisexual (pistillate flowers proximal, staminate distal), terminal, spikes or spikelike thyrses;

glands subtending each bract 2.

sessile, 1–1.2(–2) cm;

staminate flowers crowded, 1 per node;

pistillate flowers 1–3, crowded;

bracts linear-lanceolate, to 2 mm, apex acute, glands patelliform, long-stalked, 1.5–-2 mm diam.
Pedicels

absent.

Staminate flowers

sepals 2, imbricate, connate basally;

petals 0;

nectary absent;

stamens 2, connate basally;

pistillode absent.

calyx to 1 mm.
Pistillate flowers

sepals 0 or [2–]3, distinct;

petals 0;

nectary absent;

pistil [2–]3-carpellate;

styles 3 [rarely 2], connate proximally, unbranched.

sepals 0;

styles connate only at base, to 3 mm.
Fruits

capsules base persisting as [2–]3-lobed gynobase, glabrous.

Capsules

ovoid, 3.5 × 4–4.5 mm, deeply 3-lobed;

lobes of gynobase 2 mm;

columella sometimes persistent.
Seeds

globose, ovoid, ellipsoid, or cylindric, ± flattened or depressed at hilar end;

outer seed coat dry;

caruncle absent or present.

mottled light gray, cylindric-ovoid, 3.5 × 1.8 mm, smooth;

caruncle absent.
x

= 11.

Stillingia

Stillingia spinulosa
Phenology Flowering Dec–Mar(–Apr); fruiting Mar–Jun.
Habitat Dry sandy desert soils.
Elevation 0–1000 m. (0–3300 ft.)
Distribution
from USDA
Mexico; Central America; South America; s United States; West Indies; Indian Ocean Islands (Madagascar); Pacific Islands (Fiji Islands)
[BONAP county map]
from FNA
AZ; CA; NV; Mexico (Baja California, Sonora)
[WildflowerSearch map]
[BONAP county map]
Discussion

Species ca. 33 (7 in the flora).

Stillingia is distributed primarily in the warmer regions of the western hemisphere, with a major center of diversity extending from the southwestern United States through Mexico to northern Central America and another occupying the region of southern Brazil, northern Argentina, and Paraguay. Other New World species occur in Peru, southern Central America, and the southeastern United States. Outside of the western hemisphere, there are three species in Madagascar and one in Fiji. Among species in the flora area, only S. sylvatica is widespread, ranging throughout much of the southern United States from Virginia to New Mexico.

Stillingia is one of the more distinctive genera in the tribe Hippomaneae A. Jussieu ex Spach, which are generally characterized by the presence of white latex and by terminal or axillary spikelike inflorescences with one or more solitary basal pistillate flowers. Among these genera, Stillingia is distinguished by the presence of a gynobase, the hardened proximal portion of the ovary that remains as a 3-parted (or 2-parted in a few species outside the flora area) persistent base attached to the pedicel after dehiscence of the fruit. The circumscription of Stillingia has remained essentially unchanged since 1880, when Bentham first recognized the importance of the gynobase as the most important distinguishing character (D. J. Rogers 1951).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Staminate flowers in 3–15-flowered cymules; sepals of pistillate flowers 3, well developed, persistent; seeds with caruncles.
→ 2
2. Shrubs with taproots.
S. aquatica
2. Herbs or subshrubs with woody caudices or rhizomes.
→ 3
3. Leaf blades ovate, elliptic, or lanceolate, to obovate or oblanceolate, teeth without prominent blackened tips, incurved; capsules 6–12 mm diam.
S. sylvatica
3. Leaf blades linear to linear-lanceolate, teeth with prominent blackened tips, not incurved; capsules 6–8 mm diam.
S. texana
1. Staminate flowers 1 per node; sepals of pistillate flowers 0 or 3, minute and fugacious; seeds with or without caruncles.
→ 4
4. Leaf blades linear, margins entire or remotely minutely denticulate.
→ 5
5. Pistillate flowers widely spaced; glands of pistillate bracts long-stalked; seeds without caruncles.
S. linearifolia
5. Pistillate flowers crowded; glands of pistillate bracts sessile; seeds with minute caruncles.
S. paucidentata
4. Leaf blades elliptic, elliptic-spatulate, or obovate-spatulate, margins spinulose-dentate.
→ 6
6. Leaves opposite or subopposite, stipules absent, blade apices acuminate; inflorescences sessile, 1–1.2(–2) cm; glands of pistillate bracts long-stalked; seeds without caruncles.
S. spinulosa
6. Leaves alternate, stipules present, blade apices rounded to obtuse; inflorescences pedunculate, 2.5–5 cm; glands of pistillate bracts ± sessile; seeds with minute caruncles.
S. treculiana
Source FNA vol. 12, p. 233. Author: Michael J. Huft. FNA vol. 12, p. 235.
Parent taxa Euphorbiaceae Euphorbiaceae > Stillingia
Sibling taxa
S. aquatica, S. linearifolia, S. paucidentata, S. sylvatica, S. texana, S. treculiana
Subordinate taxa
S. aquatica, S. linearifolia, S. paucidentata, S. spinulosa, S. sylvatica, S. texana, S. treculiana
Name authority Garden: in C. Linnaeus, Mant. Pl. 1: 19, 126. (1767): Syst. Nat. ed. 12, 2: 611, 637. (1767) Torrey: in W. H. Emory, Not. Milit. Reconn., 151. (1848)
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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