Tragia
Tragia nigricans
noseburn
dark noseburn
erect, purple-green to reddish black, apex never flexuous.
deciduous, alternate, simple (usually 3-foliolate in T. laciniata);
stipules present, persistent;
petiole present, glands absent;
blade usually unlobed, sometimes lobed basally (sometimes deeply 3-lobed in T. laciniata) [palmately lobed], margins serrate, crenate, dentate, or entire, laminar glands absent;
venation pinnate or palmate at base, pinnate distally [palmate].
petiole 1–5 mm;
blade oblong to oblanceolate, 3–7 × 1–2.8 cm, base acute to obtuse, margins coarsely serrate, teeth apices often somewhat recurved, apex acute.
bisexual (pistillate flowers proximal, staminate distal) [unisexual], axillary, terminal, or leaf-opposed, racemes [rarely with single pistillate branch];
glands subtending each bract 0.
terminal (appearing leaf opposed), glands absent, staminate flowers 2–5 per raceme;
staminate bracts 1–2 mm.
present, staminate with persistent base, pistillate elongated in fruit.
staminate 1.3–1.6 mm, persistent base 0.2–0.4 mm;
pistillate 2–3 mm in fruit.
sepals 3–5, usually green, sometimes reddish green, not petaloid, valvate, distinct;
petals 0;
nectary absent [present];
stamens 2–6(–10)[–25], distinct or connate basally (connate 1/2 length in T. nigricans);
pistillode present [absent].
sepals 3–4, green, 1.5–2.5 mm;
stamens 4–5, filaments 0.7–1.3 mm, connate 1/2 length.
sepals 6, usually green, sometimes reddish green, not petaloid, connate basally;
petals 0;
nectary absent;
pistil 3-carpellate;
styles 3, connate basally to 1/2 [most of] length, unbranched.
sepals rhombic-lanceolate, 1–4 mm;
styles connate 1/4 length;
stigmas undulate.
capsules, usually 3 carpels maturing, except often 1 maturing in T. brevispica.
6–7 mm wide.
globose to ovoid;
caruncle absent.
dark brown, 2.5–3.2 mm.
Tragia
Tragia nigricans
Species ca. 175 (15 in the flora).
Tragia is a taxonomically difficult genus that is characterized by stinging hairs. Although many species of Tragia are twining vines, most species in the flora area are subshrubs or herbs. Some species are used medicinally for their anti-inflammatory, analgesic, vermifugic, and antihyperglycemic properties. Two sections are represented in the flora area: Tragia and Leptobotrys (Baillon) Müller Arg. Molecular phylogenetic analysis (W. M. Cardinal-McTeague and L. J. Gillespie, unpubl.) suggests that Tragia is polyphyletic and that sect. Leptobotrys (T. smallii, T. urens) should be segregated as a distinct genus; these results are supported by pollen morphology (L. J. Gillespie 1994). Tragia volubilis Linnaeus was collected from Florida once (1842–1848, F. Rugel, US), but has not been collected there since and is presumed extirpated in the flora area. This species is widespread in the Caribbean and Latin America.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The combination of relatively large, coarsely serrate leaf blades, dark stems, and filaments connate to 1/2 of length make Tragia nigricans unique within the genus in North America. It appears to be most closely related to T. leptophylla, which also has dark stems and few staminate flowers per inflorescence. Like T. leptophylla, it is found only in the Edwards Plateau, but is restricted to the eastern part; they overlap only in Uvalde County. They also differ in habitat preference.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Inflorescence glands stipitate. | → 2 |
2. Fruiting pedicels 3–7 mm; leaf blades narrowly ovate to lanceolate, bases shallowly cordate to truncate; persistent base of staminate pedicels 0.3–0.7 mm; stigmas smooth to undulate; Texas. | T. glanduligera |
2. Fruiting pedicels 7–11 mm; leaf blades ovate to triangular-ovate, bases deeply cordate; persistent base of staminate pedicels 1.8–2 mm; stigmas undulate to subpapillate; Arizona. | T. jonesii |
1. Inflorescence glands absent or sessile (T. nepetifolia and T. ramosa). | → 3 |
3. Capsules 11–13 mm wide; leaf blades 4.5–10(–13) cm, base cordate; petioles 15–85 mm; stamens 3. | T. cordata |
3. Capsules 4–11 mm wide (9–13 mm in T. smallii); leaf blades 1–8(–10) cm, base acute, obtuse, subcuneate, cuneate, truncate, subcordate, cordate, subhastate, or hastate; petioles 0–38(–41) mm; stamens 2–6(–10). | → 4 |
4. Stamens 2. | → 5 |
5. Leaf blades orbiculate to elliptic, margins serrate to crenate. | T. smallii |
5. Leaf blades usually oblanceolate to linear, sometimes elliptic, margins entire or irregularly sinuate. | T. urens |
4. Stamens 3–6(–10). | → 6 |
6. Leaves usually 3-foliolate, sometimes 3-lobed nearly to base. | T. laciniata |
6. Leaves simple, usually unlobed, sometimes lobed basally. | → 7 |
7. Stems purple-green to reddish black or brownish red to maroon-green; staminate flowers 2–5 per raceme. | → 8 |
8. Leaf blades acicular to narrowly oblong, 1–6 cm, margins usually entire, sometimes serrulate, petioles 0.5–2 mm; stamens connate basally; capsules 4–5 mm wide. | T. leptophylla |
8. Leaf blades oblong to oblanceolate, 3–7 cm, margins coarsely serrate, petioles 1–5 mm; stamens connate 1/2 length; capsules 6–7 mm wide. | T. nigricans |
7. Stems green, whitish green, reddish green, dark green, or gray-green; staminate flowers 2–80 per raceme. | → 9 |
9. Stigmas papillate. | → 10 |
10. Leaf blade margins coarsely dentate to coarsely serrate; staminate sepals reddish green; Arizona, Colorado, New Mexico. | T. nepetifolia |
10. Leaf blade margins serrate; staminate sepals green, sometimes red-tinged; c, e United States. | → 11 |
11. Staminate flowers 15–80 per raceme, distally clustered; persistent base of staminate pedicel 0.3–0.6 mm, shorter than subtending bract; pistillate sepals 1.8–5 mm. | T. betonicifolia |
11. Staminate flowers 11–40 per raceme, evenly distributed; persistent base of staminate pedicel 1–1.8 mm, longer than subtending bract; pistillate sepals 1.3–2.3 mm. | T. urticifolia |
9. Stigmas smooth, undulate, or subpapillate. | → 12 |
12. Leaf blades suborbiculate to ovate; Florida. | T. saxicola |
12. Leaf blades linear-lanceolate, lanceolate, ovate, triangular, subhastate or cordate; sc, sw United States. | → 13 |
13. Staminate flowers 2–8 per racemes; capsules with often 1 carpel maturing; stems decumbent, twining, or erect, apices usually flexuous. | T. brevispica |
13. Staminate flowers 2–20 per raceme; capsules with usually 3 carpels maturing; stems erect to trailing, apices flexuous or not. | → 14 |
14. Leaf blades usually triangular to subhastate, sometimes ovate, base cordate, hastate, or truncate; stems gray-green, apices often flexuous; stigmas undulate to subpapillate; styles connate to 1/3 length, short-exserted; stamens 3–4. | T. amblyodonta |
14. Leaf blades linear-lanceolate to narrowly ovate, base truncate to weakly cordate; stems dark green to light green, apices rarely flexuous; stigmas smooth to undulate; styles connate 1/3–1/2 length, long-exserted; stamens 3–6(–10). | T. ramosa |
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