Spreading Chinchweed

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.

Annuals, 1–30 cm (across); herbage not scented. Stems prostrate to ascending (often mat-forming, densely leafy, especially distally), puberulent (in lines or throughout). 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). Heads borne singly or in congested, (leafy) cymiform arrays. Peduncles 1–2 mm. Involucres campanulate, cylindric, or ellipsoid. 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). Ray florets 5; corollas 2.5–3.5 mm (scarcely surpassing phyllaries). Disc florets 3–17; corollas 1.8–2.5 mm (2-lipped). Cypselae 2.5–4.5 mm, strigillose; pappi of 2 (ray) or 5 (disc) lanceolate scales 1.5–2.5 mm. 2n = 24.

Pectis portoricensis Urban, Symb. Ant. 5: 276. 1907
A diffuse annual; stem branched at the base, prostrate or procumbent, rooting below, 7-15 cm. long, short-pilose along two decurrent lines; leaves oblong-linear or linear, 1-1.5 cm. long, 1.5-3 mm. wide, somewhat connate, with 5-12 pairs of bristles below the middle or along their whole length; glands small, irregularly scattered; heads solitary or in 2's or 3's in the forks or at the ends of the branches, sessile or on short peduncles less than 3 mm. long; involucre 4.5-5 mm. high, about 2 mm. broad; bracts 5, oblong, rounded or subtruncate at the apex; ray-flowers 5; ligules about 1.5 mm. long; disk-flowers 5 or 6; corollas 3 ram. long; achenes 3 mm. long; squamellae 5, those of the disk-flowers equal, of the rayflowers very unequal.
Type locality: Guayamas, Porto Rico.
Distribution: Known only from the type locality.

Pectis multisetosa Rydberg, sp. nov
A diff'use annual; stem branched at the base, prostrate, 1 dm. long or less, pilose on two decurrent lines; leaves linear-oblanceolate, 1-2 cm. long, 2-3 mm. wide, short-acuminate, setose-cilia te to near the apex; glands conspicuous, numerous, irregularly scattered; heads mostly glomerate at the ends of the branches, sessile; involucre about 5 mm. high, 2 mm. broad; bracts 5, linear-oblong, obtuse, bluntly keeled to near the apex; ray-flowers 5; ligules 1.5 mm. long; disk-flowers 4 or 5; corollas 2-2.5 mm. long; achenes 3 mm. long, sparingly hirsute ; squamellae of the disk-flowers 5, of the rays 2, linear-lanceolate, aristate-acuminate, 1.5-2 mm. long.
Type collected at Chupadero, Santa Rosa, Guatemala, 1892, Heyde &= Lux [J. D. Smith distrib. no.] 4^32 (herb. Columbia Univ.).

Pectis urceolata (Fernald) Rydberg, sp. nov
Pedis proslrala urceolata Fernald, Proc. Am. Acad. 33: 68. 1897.
A diffuse annual; stem branched at the base, 1-2 dm. high, mostly ascending, hirsute in dectuTent lines; leaves oblanceolate, entire, 2-3 cm. long, 5-8 mm. wide, obtuse, hirsute on the midribs beneath, with 6-12 pairs of bristles below and numerous scattered small glands; heads in small terminal glomerules, sessile; involucre urceolale, 7-9 mm. high, 3 mm. broad; bracts 5, oblong, hispidulous on the back, round-carinate to the apex, with acute spreading tips; glands inconspicuous, near the apex; ray-flowers 5; ligules oblong, scarcely 2 mm. long; di.sk-flowcrs 4-8; corollas 2 mm. long; achenes 4 mm. long, hirsute; squamellae of the diskflowers S, lanceolate, awn-tipped ; those of the ray-flowers 2 and somewhat larger.
TVPB LOCAi.tTV: Hacienda San Jos<-, Chihuahua.
Distkibutio.n: Known only from tlie tyjie locality. Pectisprostrata cav. Ic. 4: 12. 1797
Chthonia proslrata Cass.; DC. Prodr. S: 100. as synonym. 1836. Pedis costata Ser. & Merc; DC. Prodr. 5: 100. 1836.
A diffuse annual; stem branched at the base; branches 4-20 cm. long, decumbent or prostrate, short-pilose in decurrent lines; leaves oblanccolate-linear, entire, 1-3 cm. long, 2-4.5 mm. wide, acute, often mucronate, ciliate with 5-9 pairs of bristles below, with many distinct, scattered glands; heads axillary and terminal, the lower solitary, the upper in 2-9-cephalous gloraerules; peduncles 0-5 mm. long; involucre oblong, 5-6 mm. high, 2.5-3 mm. broad; bracts 5, oblong or linear-oblong, rounded or truncate at the apex, with a thick rounded keel extending to the apex; glands several, oblong, near the apex; ray-flowers 5; ligules oblong, 3 mm. long; disk-flowers 4-15; corollas 2-2.5 mm. long; achenes 3-4 mm. long, short-pubescent; squamellae of the ray-flowers 2, narrowly lanceolate, and 1-3 smaller bristles; those of the disk-flowers 5, unequal.
Type locality: Mexico. -, . , ^ .
Distribution: New Mexico and Arizona to Colombia and Venezuela; Florida, Cuba, and Jamaica.

Pectis prostrata, the spreading cinchweed, is a summer blooming annual plant of the genus Pectis. The development of roads and highways has created ideal habitats for Pectis prostrata. Its range is expanding along the coasts of Florida, it was recently discovered in Louisiana. It is expected to spread along the Gulf Coast and also northward along the Atlantic Coast. Autogamy has assisted Pectis prostrata to spread rapidly as suitable new habitats have become available.