Stillingia
Stillingia paucidentata
toothleaf
Mojave stillingia, Mojave toothleaf, tooth leaf
fascicled, erect, branching scattered proximally and crowded distally, (1.4–)2–3.5(–4) dm.
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.
alternate;
stipules absent;
petiole absent;
blade linear, 2–4(–6) × 0.1–0.3(–0.4) cm, base acute, margins entire or remotely denticulate, teeth without prominent blackened tips, not incurved, apex usually acute, rarely acuminate;
venation not prominent.
bisexual (pistillate flowers proximal, staminate distal), terminal, spikes or spikelike thyrses;
glands subtending each bract 2.
sessile or rarely short-pedunculate, 6–-7 cm;
staminate flowers crowded distally, 1 per node;
pistillate flowers 3–5, crowded;
bracts broadly ovate, to 1.5 mm, apex mucronulate or acuminate, glands patelliform, sessile, to 1.3 mm diam.
absent.
sepals 2, imbricate, connate basally;
petals 0;
nectary absent;
stamens 2, connate basally;
pistillode absent.
calyx to 1 mm.
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 4 mm.
capsules base persisting as [2–]3-lobed gynobase, glabrous.
oblate, 3 × 4 mm, deeply 3-lobed;
lobes of gynobase 1.5–2 mm;
columella persistent.
globose, ovoid, ellipsoid, or cylindric, ± flattened or depressed at hilar end;
outer seed coat dry;
caruncle absent or present.
brown, often mottled, ovoid, 2.3 × 1.3 mm, smooth;
caruncle minute.
= 11.
Stillingia
Stillingia paucidentata
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.)
Stillingia paucidentata is widespread in the Mojave Desert and extends into the Sonoran Desert in central Riverside County. It was reported from Arizona by T. H. Kearney and R. H. Peebles (1942, 1960) solely on the basis of the type (Palmer 517), purportedly collected in 1876 in the “Colorado Valley, near mouth of Williams River.” R. McVaugh (1943b) and McVaugh and Kearney (1943) have cast doubt on whether a number of Palmer collections with labels indicating 1876 were actually made in Arizona; they did not discuss Palmer 517 specifically. There appear to be no other specimens or reports of this species from Arizona. Because S. paucidentata is known from numerous collections in eastern San Bernardino County, California, its presence in bordering areas of Arizona cannot be completely discounted.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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 |
CA
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