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spreading chinchweed, spreading cinchweed

chinchweed

Habit Annuals, 1–30 cm (across); herbage not scented. Annuals, 5–30 cm; herbage spicy-scented.
Stems

prostrate to ascending (often mat-forming, densely leafy, especially distally), puberulent (in lines or throughout).

decumbent to erect, glabrous.

Leaves

linear to narrowly oblanceolate, 10–40 × 1.5–7 mm, margins with 4–12 pairs of setae 1–3 mm, faces glabrous (abaxial densely dotted with round oil-glands 0.1–0.3 mm).

linear, 15–35 × 1–2 mm, margins with 3–5 pairs of setae, faces glabrous (abaxial densely dotted with round oil-glands ca. 0.2 mm).

Peduncles

1–2 mm.

5–25 mm.

Involucres

campanulate, cylindric, or ellipsoid.

cylindric to narrowly fusiform.

Ray florets

5;

corollas 2.5–3.5 mm (scarcely surpassing phyllaries).

5;

corollas 3.5–4.2 mm.

Disc florets

3–17;

corollas 1.8–2.5 mm (2-lipped).

4–6;

corollas 2.2–2.5 mm (2-lipped).

Phyllaries

coherent (falling together), oblong to obovate, 5–8 × 1–3 mm (often dotted in submarginal rows and sometimes along midribs with elliptic oil-glands 0.1–0.3 mm).

coherent (falling together), linear or linear-oblanceolate, 5–7 × 1–2 mm (dotted with scattered, oval oil-glands 0.2–0.3 mm).

Heads

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

borne singly or in condensed, cymiform arrays.

Cypselae

2.5–4.5 mm, strigillose;

pappi of 2 (ray) or 5 (disc) lanceolate scales 1.5–2.5 mm.

3–3.5 mm (pericarps darkening, not swelling, ovules abortive), strigillose to short-pilose;

pappi of 2 (ray) or 5 (disc) slender, antrorsely scabrid, aristate scales 2–2.5 mm, sometimes with additional shorter scales or bristles.

2n

= 24.

= 3x = 36.

Pectis prostrata

Pectis ×floridana

Phenology Flowering Jul–Nov. Flowering Sep–Dec.
Habitat Open sites in deserts, grasslands, oak-pine-juniper woodlands, roadsides Roadsides
Elevation 0–2000 m (0–6600 ft) 0–50 m (0–200 ft)
Distribution
from FNA
AZ; FL; LA; NM; TX; Mexico; Central America; West Indies
[WildflowerSearch map]
[BONAP county map]
from FNA
FL
[BONAP county map]
Discussion

The development of roads and highways has created ideal habitats for Pectis prostrata. Its range appears to be expanding along the coasts of Florida; it was discovered in Louisiana relatively recently. It can be expected to spread along the Gulf Coast and perhaps northward along the Atlantic Coast as well. Autogamy has apparently assisted P. prostrata to spread rapidly as suitable new habitats have become available.

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

Pectis ×floridana is a triploid hybrid between P. glaucescens (2n = 48) and P. prostrata (2n = 24). The hybrids have been observed where the parental taxa grow together in roadside habitats in southern Florida. At the type locality, the hybrids were nearly as common as the parentals. Meiosis in the hybrids is very irregular; resulting pollen grains are malformed and variable in size and apparently all sterile. No fruits have been observed. Regeneration of the hybrids from season to season apparently requires new hybridization events.

The hybrids superficially resemble Pectis linearifolia from which they differ in having spicy-scented rather than lemon-scented herbage, longer peduncles, and strongly carinate phyllaries that cohere at the bases and fall together as a group.

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

Source FNA vol. 21, p. 224. FNA vol. 21, p. 226.
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. papposa, P. rusbyi, P. ×floridana
P. angustifolia, P. cylindrica, P. filipes, P. glaucescens, P. humifusa, P. imberbis, P. linearifolia, P. linifolia, P. longipes, P. papposa, P. prostrata, P. rusbyi
Name authority Cavanilles: Icon. 4: 12, plate 324. (1797) D. J. Keil: Sida 11: 389. (1986)
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