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Published In: Opera Varia 244. 1758. (Opera Var.) Name publication detail

Project Name Data (Last Modified On 8/29/2017)
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Dalea L. (Barneby, 1977)

Plants annual or perennial herbs (shrubs elsewhere). Stems prostrate to erect, branched, unarmed, glabrous or hairy, the hairs simple, sometimes also gland-dotted. Leaves alternate, odd-pinnately compound or rarely trifoliate, short-petiolate or sessile, the petiole and rachis often gland-dotted, the rachis usually appearing somewhat flattened or narrowly winged, the leaflets (3)5–35, mostly opposite. Stipules linear to narrowly triangular, mostly inconspicuous, sometimes shed early. Leaflets variously shaped, symmetric at the sessile or minutely stalked base, variously shallowly notched to truncate, rounded, or pointed at the tip, the margins entire, the surfaces glabrous or hairy, usually noticeably gland-dotted, 1-veined. Inflorescences variously open to dense, elongate or headlike spikes, in some species sometimes drooping with age, terminal on the stems and branches, the flowers subtended by often conspicuous bracts, these variously shaped, often gland-dotted, sometimes shed early; a pair of minute, inconspicuous bractlets also present in some species. Calyces not 2-lipped, 5-lobed, somewhat zygomorphic (the uppermost lobe often longer than the others), the tube shorter than to more commonly longer than the lobes, 10-ribbed, gland-dotted, the lobes variously shaped, but angled or tapered to sharply pointed tips, the margins often conspicuously hairy. Corollas papilionaceous (but sometimes very weakly so, with the wings and keel petals similar), variously colored; the banner with a long, stalklike base, the expanded portion variously heart-shaped or kidney-shaped to broadly oblong-ovate or nearly circular; the wings attached to the side or tip of the filament tube, elliptic to more or less strap-shaped; the 2 keel petals either similar to the wings or strongly overlapping to more or less fused, not boat-shaped. Stamens 5–10, the filaments all fused, the tube shorter than to longer than the free portions, sometimes split more deeply on 1 side, the anthers small, orange to yellow or blue, attached near the midpoint, all similar in size, the connective between the sacs sometimes with a gland. Ovary asymmetrically ovoid, sessile, glabrous or hairy, the style usually curved, the stigma small and terminal. Fruits short legumes more or less enclosed in the persistent calyx, asymmetrically obovoid, plump, sessile, broadly rounded to more or less truncate at the tip and usually with a minute tooth (the persistent style base) along the margin, the surfaces glabrous or hairy, sometimes gland-dotted, often thinner and more or less translucent toward the base, 1-seeded, indehiscent. Seeds 1.5–3.0 mm long, oblong-ovoid to asymmetrically kidney-shaped, somewhat flattened, the surfaces yellow to dark brown, smooth or in some species some of them wrinkled, shiny. About 160 species, North America to South America.

Dalea has a center of diversity in the southwestern United States and portions of Mexico. Many species have a thick root system which undoubtedly helps them survive in their often dry habitats. The genus is of little economic importance, although several species are important forage plants and a number are cultivated as ornamentals. McGregor (1986) noted that prairie clovers (in particular D. candida and D. purpurea), are selectively grazed by livestock and tend to disappear quickly when lands are overgrazed.

Barneby’s (1977) circumscription of Dalea includes some groups that formerly were treated as separate genera, such as Kuhnistera Lam., Parosela Cav., Petalostemon Michx., and Thornbera Rydb. These were distinguished by details of petal shape and attachment on the stamen tube and the number of functional stamens. Shared characters that separate Dalea (as circumscribed here) from its relatives include the petals arising from the anther column, two ovules positioned side-by-side in the ovary (one of these abortive), and a base chromosome number of By this definition, some of the mostly shrubby, non-Missouri groups of species traditionally included in Dalea were segregated into the genera Marina Liebm. and Psorothamnus Rydb. Missouri species formerly included in Petalostemon, in which four of the petals arise from the rim of the stamen tube alternating with five anther-bearing filaments, include D. candida, D. gattingeri, D. multiflora, D. purpurea, and D. villosa. The wing and keel petals of these species are sometimes interpreted as staminodes, with the free banner petal all that remains of the true corolla (Wemple and Lersten, 1966). Alternatively, these may be true petals that have migrated to the rim of the staminal tube, with the loss of one whorl of stamens. In either case, such flowers are not truly papilionaceous in morphology because the wing and keel petals are not strongly differentiated and the keel petals are not fused. The other species of Dalea in Missouri have nine or ten stamens and petals attached to the sides of the stamen tube.


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1 Blades of the main stem leaves (excluding any smaller leaves in axillary fascicles) with (9–)13–35 leaflets; roots yellowish orange to reddish orange (2)
+ Blades of the main stem leaves (excluding any smaller leaves in axillary fascicles) with (3)5–13 leaflets; roots dark brown to black (yellow in D. enneandra) (3)
2 (1) Stems (excluding the inflorescence axes) and leaves glabrous; plants annual, taprooted; stamens 9 or 10; petals white or rarely pale bluish-tinged, the wing and keel petals attached along the side of the stamen tube Dalea leporina
+ Stems and leaves noticeably hairy; plants perennial with a branched rootstock; stamens 5; petals pink to reddish purple, the wing and keel petals attached at the tip of the stamen tube Dalea villosa
3 (1) Inflorescences loosely flowered, the axis readily visible between the flowers; stamens 9; wing and keel petals attached along the side of the stamen tube, the stamen tube noticeably longer than the free portion of the filaments; bracts broadly ovate to broadly obovate, strongly cupping the flowers, the margin with a conspicuous, thin, pale, narrow band; roots yellow Dalea enneandra
+ Inflorescences densely flowered, the axis not easily visible between the flowers except sometimes at fruiting (occasionally more or less visible in pressed specimens); stamens 5; wing and keel petals attached at the tip of the stamen tube, the stamen tube about as long as the free portion of the filaments; bracts variously linear to triangular or ovate, not strongly cupping the flowers the margin lacking a pale band; roots dark brown to black (4)
4 (3) Petals white; calyces glabrous; axis of the inflorescence glabrous or occasionally minutely and inconspicuously hairy (viewing the axis requires removal of flowers or fruits) (5)
+ Petals purple; calyces densely hairy; axis of inflorescence densely pubescent with short, bristly hairs (viewing the axis requires removal of flowers or fruits) (6)
5 (4) Plants with 1–4 stems; leaf blades with rachis 10–30 mm long, leaflets 5–30 mm long, the lowermost leaves often with larger leaflets than those of the upper leaves; inflorescences 1–7 per stem, 2–5 cm long, ovoid or cylindric; bracts subtending the flowers 5–6 mm long, longer than the calyces of the associated buds (usually shed by the time the flowers open Dalea candida
+ Plants in bushy clumps of 5 or more stems; leaf blades with the rachis 5–14 mm long, leaflets 3–7(–13) mm long, mostly uniform over the length of the stem; inflorescences more than 7 per stem, usually numerous, subglobose, 5–15 mm long; bracts subtending the flowers 1.4–2.4 mm long, shorter than the calyces of the associated buds (usually shed by the time the flowers open) Dalea multiflora
6 (4) Stems 10–40 cm long, low, loosely ascending from a spreading base or prostrate throughout; inflorescences 4–8 cm long, becoming lax or sinuous; bracts evenly hairy above the papery base Dalea gattingeri
+ Stems 50–80 cm long, erect to strongly ascending or slightly arched; inflorescences 2–5 cm long, cylindric, dense, remaining straight or nearly so; bracts hairy in a narrow band above the base and below the tip Dalea purpurea
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