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Tweedy's ticktrefoil

creeping beggarweed, Spanish clover, Spanish tick-trefoil, zarzabacoa comun

Habit Herbs, perennial. Herbs, subshrubs, or shrubs, perennial; stoloniferous or rhizomatous.
Stems

ascending or erect, usually striate, angled, 30–100 cm, densely uncinate-puberulent to -pubescent and sparsely glutinous-pilose.

erect or ascending, to 300 cm, pubescent or glabrescent.

Leaves

trifoliolate;

stipules persistent, ovate, 7.5–14.5 mm;

petiole 40–90 mm;

leaflet blades narrowly ovate to ovate or broadly ovate, thick, leathery, apex acute, usually pale-blotched along midrib adaxially, surfaces uncinate-puberulent to -pubescent and villous;

terminal blade 40–120 × 20–66 mm, length 2 times width.

trifoliolate;

stipules usually persistent, narrowly ovate-deltate, 5–10 mm;

petiole usually 15–20 mm;

leaflet blades elliptic to ovate, apex obtuse or acute, surfaces finely spreading-villosulous to substrigose abaxially, uncinate-puberulent or glabrescent adaxially;

terminal blade 20–90 × 15–45 mm, length 1.5–4 times width.

Inflorescences

branched or unbranched;

rachis densely uncinate-puberulent to -pubescent and glutinous-villous;

primary bracts ovate to broadly ovate, 7–10 mm.

unbranched;

rachis densely patent uncinate-pubescent;

primary bracts caducous, narrowly ovate, 6–7 mm.

Pedicels

8–25 mm, patent uncinate-pubescent and pilose.

persistent with calyx-remnant at top after loments drop, 5–9 mm.

Flowers

calyx 3–5 mm, puberulent and pubescent, ± glutinous, tube 1.2–1.5 mm;

abaxial lobes 2.5–4 mm, lateral lobes 1.5 mm;

corolla white, 7–8 mm.

calyx 2–3.5 mm, uncinate-puberulent, lobes pilose, tube 1 mm;

abaxial lobes 1.5–2.5 mm, lateral lobes 1–2 mm;

corolla purple, 5–8 mm.

Loments

sutures nearly equally crenate;

connections adaxial, 1/4 as broad as segments;

segments (2 or)3–5(or 6), subrhombic, 6–8 × 4 mm, obtusely angled abaxially, somewhat angled adaxially, densely uncinate-pubescent throughout;

stipe 2–4 mm.

sutures symmetrically crenate abaxially, straight or slightly sinuate adaxially;

connections central, 1/2–2/3 as broad as segments;

segments 4–8, semiobovate, 3.5–5 × 2.5–3 mm, broadly rounded abaxially, straight or barely convex adaxially, uncinate-puberulent;

stipe 1.5–2 mm.

2n

= 22.

Desmodium tweedyi

Desmodium incanum

Phenology Flowering early summer. Flowering spring–fall.
Habitat Woodlands near creeks, usually calcareous soils. Pine-palmetto flatwoods, woodland borders, lawns, ruderal sites, disturbed or waste areas.
Elevation 200–800 m. (700–2600 ft.) 0–50 m. (0–200 ft.)
Distribution
from FNA
OK; TX
[BONAP county map]
from FNA
AL; FL; GA; TX; Central America; South America; Mexico (Chiapas, Jalisco, Oaxaca, Quintana Roo, Tamaulipas, Veracruz); West Indies [Introduced in North America; introduced also in Asia (Taiwan), Africa, Indian Ocean Islands (Mauritius, Reunion), Pacific Islands, Australia]
[WildflowerSearch map]
[BONAP county map]
Discussion

Desmodium tweedyi is known from the Edwards Plateau area and north-central Texas northward to central Oklahoma.

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

Desmodium incanum may be distinguished by its long-persistent stipules usually fused and nearly surrounding the stem, at least when young, and by its pedicels which are usually borne singly and are each subtended by one primary bract and two (lateral) secondary bracts (B. G. Schubert 1980).

Desmodium incanum was long known as D. canum Schinz & Thellung (= Meibomia cana S. F. Blake) based on the illegitimate Hedysarum canum J. F. Gmelin, a superfluous name for H. racemosum Aublet. The complex nomenclatural history was elaborated by D. H. Nicolson (1978) and L. C. P. Lima et al. (2012, 2014). Hedysarum canescens Miller (1768) is a later homonym of H. canescens Linnaeus (1753), thus illegitimate, and pertains here. Hedysarum canum J. F. Gmelin is a superfluous name for H. racemosum Aublet; Meibomia cana S. F. Blake was intended as a new combination based on that name.

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

Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Desmodium Fabaceae > subfam. Faboideae > Desmodium
Sibling taxa
D. arizonicum, D. batocaulon, D. canadense, D. canescens, D. cinerascens, D. cuspidatum, D. floridanum, D. grahamii, D. gramineum, D. illinoense, D. incanum, D. intortum, D. laevigatum, D. lindheimeri, D. lineatum, D. marilandicum, D. metcalfei, D. nuttallii, D. ochroleucum, D. paniculatum, D. procumbens, D. psilocarpum, D. psilophyllum, D. retinens, D. rosei, D. rotundifolium, D. scopulorum, D. scorpiurus, D. sessilifolium, D. strictum, D. tenuifolium, D. tortuosum, D. triflorum, D. viridiflorum, D. ×humifusum
D. arizonicum, D. batocaulon, D. canadense, D. canescens, D. cinerascens, D. cuspidatum, D. floridanum, D. grahamii, D. gramineum, D. illinoense, D. intortum, D. laevigatum, D. lindheimeri, D. lineatum, D. marilandicum, D. metcalfei, D. nuttallii, D. ochroleucum, D. paniculatum, D. procumbens, D. psilocarpum, D. psilophyllum, D. retinens, D. rosei, D. rotundifolium, D. scopulorum, D. scorpiurus, D. sessilifolium, D. strictum, D. tenuifolium, D. tortuosum, D. triflorum, D. tweedyi, D. viridiflorum, D. ×humifusum
Synonyms Meibomia tweedyi Hedysarum incanum, Aeschynomene incana, D. ancistrocarpum, D. canum, D. frutescens, D. frutescens var. amplyophyllum, D. malacophyllum, D. mauritianum, D. supinum var. amblyophyllum, H. ancistrocarpum, H. malacophyllum, H. mauritianum, H. racemosum, Meibomia adscendens var. incana, M. incana, M. malacophylla, M. supina
Name authority Britton: Trans. New York Acad. Sci. 9: 183. (1890) (Swartz) de Candolle in A. P. de Candolle and A. L. P. P. de Candolle: Prodr. 2: 332. (1825) — name conserved
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