FNA: Crotalaria rotundifolia var. linaria vs. Crotalaria

Phenology

Flowering Dec–May(–Aug).

Habitat

Beaches, disturbed sandy sites, pine-palmetto scrub, hammocks, pine woods.

Elevation

0–30 m. (0–100 ft.)

Distribution

FL

United States; Mexico; Central America; South America; West Indies; Europe; Asia; Africa; Indian Ocean Islands; Pacific Islands; tropics and subtropics; mostly eastern and southern tropical Africa [Introduced in Australia]

[BONAP county map]

Discussion

D. R. Windler (1974) recognized var. vulgaris, distinguished by spreading hairs on stems, from var. rotundifolia with appressed hairs on stems, but the difference is slight and sometimes subjectively interpreted. In contrast, var. linaria is a much more easily recognized variant, although it has recently been considered part of a polymorphic population system in Florida (Windler; D. Isely 1998).

Plants with all leaf blades linear, proximal to distal, are common on Big Pine Key and in the southern half of peninsular Florida with collections seen from Broward, Citrus, Dade, Hernando, Hillsboro, Lee, Manatee, Marion, Martin, Monroe, Palm Beach, Pinellas, Polk, and Sarasota counties. Collections of plants with leaf blades elliptic to obovate on the proximal one-third of the stems, quickly becoming linear distally, are scattered through some of the same counties as well as slightly farther north (for example, Alachua and Lake counties). Typical Crotalaria rotundifolia also occurs in the southern counties (for example, Brevard, Collier, Miami-Dade, Martin, Polk, and Sarasota counties). Plants with linear leaf blades on the distal two-thirds of the stems are sharply restricted to the southern half of Florida and, in view of their striking morphological distinction, it seems useful to formally recognize them. By doing so, it is acknowledged that sympatry of vars. linaria and rotundifolia suggests that some degree of reproductive isolation may exist.

Forms of var. linaria and Crotalaria purshii may be similar in overall appearance (especially on herbarium sheets), but the two are allopatric, and C. purshii has erect to ascending-erect stems, leaves not densely overlapping with mid stem nodes 30–60 mm, and leaflet surfaces glabrous adaxially, compared to C. rotundifolia var. linaria, which usually has prostrate stems, leaves densely overlapping with mid stem nodes 4–15(–25) mm, and leaflet surfaces strigose.

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

Species ca. 600 (15 in the flora).

Crotalaria biflora Linnaeus (native to India) was collected in 1959 as a waif on chrome ore piles in Newport News, Virginia (C. F. Reed 1964). The species is an annual, distinguished as hirsute-villous to subsericeous, stems prostrate, 5–12 cm, leaves sessile, unifoliolate, blades ovate to oblong or oblong-ovate, surfaces villous-hirsute, flowers one or two, on axillary peduncles, and hirsute, ovoid to cylindrical-ovoid legumes.

Crotalaria alata Buchanan-Hamilton ex D. Don (native to Himalayan Asia) was collected in 1939 as an escape in Gainesville, Florida (W. A. Murrill s.n., MO); subsequently, it has not been recorded in the flora area. The species is perennial, distinguished as hirsute to strigose-hirsute, stems erect, 10–20 cm, leaves unifoliolate, blades lanceolate to elliptic-lanceolate or elliptic, stipules decurrent, forming wings on internodes, and apically bilobed, flowers in terminal and axillary racemes, 4–10 cm, and legumes glabrous.

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

Key

1. Leaves 3-foliolate.	→ 2
2. Leaflet blades 5–15(–35) mm; legumes 7–20 mm.	→ 3
3. Stems mostly decumbent to prostrate, minutely and sparsely strigillose; legumes.	C. pumila
3. Stems erect to decumbent, loosely strigose to strigose-hirsute; legumes 7–10 mm.	C. virgulata
2. Leaflet blades (10–)20–130(–180) mm; legumes (16–)18–70 mm.	→ 4
4. Leaflet blades linear to linear-lanceolate, elliptic-lanceolate, or lanceolate, lengths 5–10 times widths.	→ 5
5. Racemes 12–26(–40)-flowered; corollas 8–11 mm; legumes 4–6 mm diam.	C. lanceolata
5. Racemes 4–12-flowered; corollas 18–20 mm; legumes (10–)15–20 mm diam.	C. ochroleuca
4. Leaflet blades obovate, ovate, elliptic-obovate, elliptic-oblanceolate, elliptic, elliptic-lanceolate, or spatulate-obovate, lengths 1.3–4.5 times widths.	→ 6
6. Stipules absent; leaflet blades elliptic to elliptic-lanceolate, or elliptic-oblanceolate, 40–100(–140) mm, lengths 3–4.5 times widths; calyces basally truncate and deflexed against pedicels.	C. trichotoma
6. Stipules usually present (persistent or caducous); leaflet blades elliptic, ovate, obovate, elliptic-obovate, or spatulate-obovate, (10–)20–70 mm, lengths 1.3–2.5 times widths; calyces sometimes basally truncate, not deflexed against pedicels.	→ 7
7. Legumes 5–6 mm diam., slightly to conspicuously curved, minutely puberulent to glabrate; stems strigose; leaflet surfaces strigillose abaxially, glabrous adaxially.	C. pallida
7. Legumes 10–15 mm diam., straight, villous-hirsute to hispid-hirsute; stems hirsute-villous to strigose-hirsute; leaflet surfaces glabrous or hairy on abaxial midvein.	C. incana
1. Leaves unifoliolate.	→ 8
8. Corollas usually blue to lavender, sometimes white or pale yellow tinged blue; stipules present, often encircling nodes.	C. verrucosa
8. Corollas bright yellow; stipules present and not encircling nodes, or absent.	→ 9
9. Stipules decurrent on mid and distal stems.	→ 10
10. Herbs annual; stems erect to decumbent, hirsute-pilose; leaflet blade lengths 4–8 times widths.	C. sagittalis
10. Herbs perennial; stems decumbent, prostrate, ascending, or erect, strigose or strigose-sericeous to hirsute-villous; leaflet blade lengths 1–12 times widths.	→ 11
11. Leaflet blades linear-lanceolate, linear-oblanceolate, linear, oblong, or elliptic (narrower distally), lengths (2–)4–10 times widths, surfaces glabrous adaxially; stems erect to ascending.	C. purshii
11. Leaflet blades broadly elliptic to elliptic-ovate, ovate, broadly lanceolate, linear, linear-lanceolate, or obovate-oblanceolate, lengths 1–12 times widths, surfaces strigose to strigose-hirsute adaxially; stems prostrate to decumbent or ascending.	C. rotundifolia
9. Stipules, when present, not decurrent on stems.	→ 12
12. Herbs perennial; stipules absent; leaflet blades (5–)8–19 mm; stems 2–10 cm; corollas 8–9 mm.	C. avonensis
12. Herbs annual; stipules usually present; leaflet blades 30–150 mm; stems 30–200(–400) cm; corollas 15–25 mm.	→ 13
13. Stipules ovate to ovate-lanceolate, 4–7 mm; floral bracts 5–8 mm, persistent; stems glabrous.	C. spectabilis
13. Stipules, when present, filiform or setaceous, 1–2 mm; floral bracts 2–5 mm, persistent or caducous; stems strigose or strigose-sericeous.	→ 14
14. Leaflet blades obovate to spatulate or oblanceolate, 30–80 mm, lengths.	→ 2
2. 2–3(–4) times widths; stems 30–90 cm.	C. retusa
14. Leaflet blades linear-elliptic to oblong, 50–150 mm, lengths 2.5–4 times widths; stems 100–200(–400) cm.	C. juncea