Tetraneuris argentea
Tetraneuris
perkysue
bitterweed, four-nerve daisy
± branched, branches notably thickened distally.
1–8(–12), erect, leafy, ± branched distally.
1–60, erect or ± decumbent, unbranched or sparingly branched distally.
basal and cauline, entire, usually densely strigoso-canescent, ± gland-dotted;
basal leaves tightly clustered, blades spatulate to oblanceolate;
proximal cauline blades oblanceolate;
mid blades oblanceolate to linear-oblanceolate, 2.5–5 mm wide;
distal blades linear-lanceolate to linear.
all basal, or basal-proximal, or basal and cauline; alternate; petiolate or sessile;
blades (usually with distinct midribs) mostly oblanceolate to linear or filiform, sometimes lobed, ultimate margins usually entire, sometimes toothed, faces glabrous or ± hairy, eglandular or ± gland-dotted.
2–13.5 cm, usually densely hairy.
(5–)7–10 × 8–15 mm.
hemispheric to campanulate 6–20 mm diam.
hemispheric to conic, shallowly pitted or smooth, epaleate.
8–14;
corollas 11.8–17 mm.
0 or 7–27, pistillate, fertile;
corollas (usually marcescent) yellow (laminae fan-shaped to oblanceolate, usually 3-lobed).
25–75(–100+);
corollas yellow proximally, yellow or rarely purplish distally, 2.8–3.8 mm.
20–250+, bisexual, fertile;
corollas yellow proximally, yellow or purplish distally, tubes shorter than cylindric to cylindro-campanulate throats, lobes 5, ± deltate.
11–60+ in 3 series (mostly spreading to erect in fruit, distinct, herbaceous; outer with or without scarious margins, abaxial faces ± hairy; mid usually same number as, alternating with, and similar to outer, almost always with ± scarious margins; inner narrower than others, margins scarious).
8–11, 4–6.5 mm, margins 0–0.3 mm wide, usually scarious, abaxial faces densely hairy.
1–10(–30) per plant (1–7 per stem), borne singly or in paniculiform to corymbiform arrays.
radiate or discoid, borne singly or in paniculiform to corymbiform or fastigiate arrays.
2.4–3.1 mm;
pappi of 5–6 obovate, aristate scales 2.1–3.5 mm.
± obpyramidal, moderately to densely hairy;
pappi persistent, of 4–8 usually aristate, scales.
= 15.
= 30, 60.
Tetraneuris argentea
Tetraneuris
Species 9 (9 in the flora).
Here, strigoso-canescent refers to often silvery induments (hairs tightly appressed, relatively short, 1–1.5 mm) of Tetraneuris argentea and T. acaulis var. acaulis. Such induments contrast with lanuginose or sericeous induments (hairs spreading, ca 1.5–3 mm) in other taxa, including T. ivesiana and the other three varieties of T. acaulis.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Annuals | T. linearifolia |
1. Perennials (with caudices) | → 2 |
2. Caudices: branches not notably thickened distally; leaves all basal-proximal (not tightly clustered, internodes often evident) | → 3 |
2. Caudices: branches notably thickened distally; leaves all basal or basal and cauline (basal leaves tightly clustered, internodes usually not evident) | → 4 |
3. Stems erect; leaves sparsely to densely hairy, not woolly; Colorado, Kansas,Nebraska, New Mexico, Oklahoma, Texas | T. scaposa |
3. Stems erect or ± decumbent; leaves moderately to densely woolly; s Texas | T. turneri |
4. Leaves basal and cauline | → 5 |
4. Leaves all basal | → 6 |
5. Leaf blades ± densely strigoso-canescent | T. argentea |
5. Leaf blades glabrous or sparsely to moderately lanuginose to sericeous | T. ivesiana |
6. Ray florets 0 (leaves densely hairy, not strigoso-canescent; Yavapai County,Arizona) | T. verdiensis |
6. Ray florets usually 7–27 (if 0, leaves strigoso-canescent; widespread) | → 7 |
7. Rays 14–27; pappus scales usually non-aristate; Ontario, Illinois, Ohio | T. herbacea |
7. Rays 7–15(–21); pappus scales aristate; North Dakota to Texas and west | → 8 |
8. Leaves (midribs usually distinct) glabrous or usually sparsely, sometimes moderately or densely hairy (not strigoso-canescent or sericeous), gland-dotted; outer phyllaries 4–8, margins (0.3–)0.5–1.2 mm wide, usuallyconspicuously scarious | T. torreyana |
8. Leaves (midribs not very distinct) glabrous or ± hairy, often lanuginose, sericeous, or strigoso-canescent, eglandular or ± gland-dotted; outer phyllaries 6–12, margins 0–0.4 mm wide, sometimes slightly scarious | T. acaulis |
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