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chinchweed, common chinchweed, manybristle chinchweed

yerba de San Juan

Habit Annuals, 1–30 cm (often forming rounded bushes); herbage spicy-scented. Annuals or perennials, 2–25 cm (across; bases often ± woody); herbage not scented.
Stems

ascending, glabrous or puberulent.

prostrate (mat-forming, densely leafy), puberulent (in decurrent lines).

Leaves

linear, 10–60 × 1–2 mm, margins with 1–3 pairs of setae, faces glabrous (dotted on margins with round to oval oil-glands 0.3–0.5 mm).

oblong-oblanceolate to obovate, 3–17 × 1.5–4 mm wide, margins with 2–6 pairs of setae 1–2 mm, faces glabrous (dotted with scattered, round oil-glands 0.1–0.2 mm).

Peduncles

3–40 mm.

1–12 mm.

Involucres

campanulate to cylindric.

campanulate.

Ray florets

(7–)8(–10);

corollas 3–8 mm.

5;

corollas 3.5–5 mm.

Disc florets

6–34;

corollas 2–5.5 mm (weakly 2-lipped, glabrous or glandular-puberulent).

12–21;

corollas 2.5–3.5 mm (2-lipped).

Phyllaries

distinct, linear, 3–8 × 0.5–1.7 mm (dotted with 1–5 subterminal oil-glands plus 2–5 pairs of submarginal oil-glands).

distinct, obovate, 4.5–6 × 2–4 mm (faces densely dotted with scattered, circular oil-glands 0.05–0.2 mm).

Heads

in congested or open, cymiform arrays.

borne singly or in congested, (leafy) cymiform arrays.

Cypselae

2–5.5 mm, strigillose to short-pilose (hair tips curled, bulbous);

ray pappi usually coroniform, rarely of 1+ awns or bristles 1–4 mm;

disc pappi usually of 16–24, subplumose bristles 1.5–4 mm, rarely coroniform.

2.5–4 mm, mostly puberulent (ray cypselae abaxially glabrous);

ray pappi of 2–3 slender, aristate scales 1.5–2.5 mm plus 2–10 lacerate scales or bristles;

disc pappi of 4–15, antrorsely scabrid bristles or aristate scales 2–3 mm plus 0–15 bristles or scales.

2n

= 72.

Pectis papposa

Pectis humifusa

Phenology Flowering year round.
Habitat Sandy soils
Elevation 0–10 m (0–0 ft)
Distribution
from FNA
AZ; CA; NM; NV; TX; UT; nw Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
FL; West Indies (Puerto Rico, Lesser Antilles); South America (Suriname)
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

Pectis papposa generally flowers following summer monsoon rains in the desert of southwestern United States and northern Mexico. In favorable years, it becomes an aspect dominant, coloring wide areas of the desert with its bright yellow heads.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Pectis humifusa has been reported once from Florida (D. J. Keil 1975c), where it is probably adventive. In the Lesser Antilles, it occurs most frequently in the salt spray zone near the seashore; on some islands, it occurs inland as well.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Phyllaries 3–5 mm; disc florets 6–14(–18); disc pappi 1–2.5 mm
var. papposa
1. Phyllaries 5–8 mm; disc florets 12–24(–34); disc pappi 2.5–4 mm
var. grandis
Source FNA vol. 21, p. 227. FNA vol. 21, p. 225.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Pectidinae > Pectis Asteraceae > tribe Heliantheae > subtribe Pectidinae > Pectis
Sibling taxa
P. angustifolia, P. cylindrica, P. filipes, P. glaucescens, P. humifusa, P. imberbis, P. linearifolia, P. linifolia, P. longipes, P. prostrata, P. rusbyi, P. ×floridana
P. angustifolia, P. cylindrica, P. filipes, P. glaucescens, P. imberbis, P. linearifolia, P. linifolia, P. longipes, P. papposa, P. prostrata, P. rusbyi, P. ×floridana
Subordinate taxa
P. papposa var. grandis, P. papposa var. papposa
Name authority Harvey & A. Gray: Mem. Amer. Acad. Arts, n. s. 4: 62. (1849) Swartz: Prodr., 114. (1788)
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