114.  Dalea hemsleyana (Rose) Bullock

(Plate CV)

Suffruticose becoming shrubby, many-stemmed, the mature plant of symmetrically bushy outline ±3.5-7 dm tall and as broad or broader, at anthesis appearing glabrous to the spikes but the truly glabrous (or distally puberulent) main cauline leaves subtending silvery-pubescent leaf-buds (by late anthesis becoming short spurs), the old wood brown and furrowed, the young stems livid, freely branching, densely verrucose with small but prominent, often grainlike, lurid or pallid warts, the young foliage sparse, green, the leaflets of thick texture, paler and dotted beneath; leaf-spurs 0.4-1 (1.5) mm long; stipules triangular-subulate, livid, 0.3-1.2 mm long; intrapetiolular glands small, either impressed or prominent; post-petiolular glands nipple-shaped or conic, greenish or livid; main cauline leaves mostly 4-14 (20) mm long, subsessile, with narrowly thick-margined, ventrally grooved rachis and 4-7 (8) pairs of usually crowded, obovate-cuneate to oblanceolate, emarginate or retuse, folded leaflets 1-3 (4) mm long, the spur-leaves, when developed, smaller, with fewer smaller leaflets of the same type; peduncles leaf-opposed and then terminal to all the branchlets, 2-12 cm long; spikes very dense and conelike, globose or broadly ovoid, without petals 7-10.5 (12) mm diam, the densely villosulous axis 2-14 mm long; bracts 2—3.5 mm long, dimorphic, the outer ones persistent, broadly ovate to elliptic-ovate, livid, glabrous or nearly so and gland-verruculose dorsally, ciliolate, the inner ones tardily deciduous (half fast between the crowded calyces) oblanceolate, densely pilosulous dorsally in lower half, glabrate and livid distally, all silky within above the middle; calyx 3.4-5.4 mm long, densely pilosulous externally with spreading-ascending spiral hairs up to 0.45-0.65 mm long, the tube 2-2.8 mm long, sometimes but not always recessed behind the banner, the ribs becoming prominent, orange-brown, the intervals membranous, eglandular or charged with 1-3 minute, transparent glands visible only from within, the triangular-acuminate, livid or nigrescent, gland-spurred teeth usually a little unequal, the dorsal one 1.3-2.7 mm long (as long or commonly shorter than the tube), the ventral pair shorter but hardly broader; petals bicolored, the banner opening cream-white (sometimes purple-tipped), rubescent, the inner ones vivid rose- or magenta-purple, all eglandular, the wings and keel elevated 1.1-1.5 mm above the hypanthium rim; banner 4.7-6.4 (7) mm long, the claw 2-2.9 (3.4) mm, the deltate-ovate blade cordate at the open base, reflexed through ± 40°, 2.5-4.3 mm long, 2.4-4.8 mm wide; wings 4.5-7.2 mm long, the claw 1.5-2.2 mm, the ovate-elliptic to lance-oblong blade 3.3-5.6 mm long, 1.2-2.4 mm wide; keel 5.3-8 mm long, the claws 2.2-3.1 mm, the broadly ovate-elliptic blades 3.5-5.4 mm long, 2.1-2.8 mm wide; androecium 5.5-8.5 mm long, the longest filament free for 2.1-2.8 mm, the gland- tipped anthers 0.7-0.8 mm long; pod (not seen fully formed) ± 2.5 mm long, apparently deltate in profile, the style-base terminal but excentric, the valves glabrous and hyaline in the lower half, thinly papery and densely pilosulous distally; n — 7 (Spellenberg, 1973).-Collections: 9 (iv).

Colonial along gullies and on open plains in arid grassland, 2100-2450 m (± 7000-8150 ft), known only from s. Zacatecas and w. San Luis Potosi, but closely approaching and to be expected in Aguas Calientes, extreme n.-e. Jalisco, and s.-e. Durango. —Flowering August to November. —Material: San Luis Potosi "San Luis", Schaffner 586/785 (M, MEXU, NY, US); 25 mi s.-w. of San Luis, Ripley & Barneby 13,326(CAS, MEXU, MICH, NY, US). Zacatecas. 5 mi w. of Zacatecas, Spellenberg & Dunford 2940 (NY); s. corner of the state, n.-e. of Ojuelos de Jalisco, Ripley & Barneby 13,330 (CAS, MEXU, MICH, K, NY, US); Malpaso, 16 mi s.-w. of Zacatecas, Ripley & Barneby 13,456 (CAS, MEXU, MICH, NY, US); Zacatecas, Purpus 419 (UC); Fresnillo (vidi!); pass through Sierra Papanton, border of Durango, Gentry 8450 (MEXU, UC, US); ibid., near El Calabazal, Ripley & Barneby 14,156 (CAS, MEXU, NY, US).

Dalea hemsleyana (Rose) Bullock, Kew Bull. 1939: 196. 1939, based on Parosela hemsleyana (William Botting Hemsley, 1843-1924) Rose, Contrib. U. S. Nat. Herb. 10: 104. 1906. — "Type...collected by Parry and Palmer near San Luis Potosi, 1878 (no. 154)."—Holotypus, US! isotypi, F, NY (2 sheets), US\—Dalea ramosissima sensu Hemsl., Biol. Centr.-Amer., Bot. 1: 245, non Benth.

On the steppes and desert grasslands of Mexico’s Meseta Central, southward from the Tropic, only two daleas, D. hemsleyana and D. dorycnioides, share the features of densely warted stems and subglobose conelike flower-spikes subtended by persistent bracts. Mature plants of both species form small, intricately branching bushes, with the condensed foliage of the confirmed xerophyte, and in due season very numerous and showy heads of flower. In D. dorycnioides the stems of the year and all the leaves are gray- or white-tomentulose, and even in the largest leaves the leaflets are normally only 2-4 pairs; in D. hemsleyana the young stems are glabrous like the main cauline leaves, which are composed of mostly 4-7 pairs of leaflets. Furthermore the two species are ecologically separated, as D. dorycnioides is strongly, perhaps obligately calciphile, and therefore follows the limestones of the Sierra Madre Oriental from Nuevo Leon southward, while D. hemsleyana is on the old eruptive rocks that form the backbone of Zacatecas. They are therefore, despite similar flowers and inflorescences, easily separated in practice. But although the plant-body of D. hemsleyana is, at least up to anthesis, glabrous or nearly so, late in the season densely silvery-tomentulose leaf-buds appear in the axils of the drought-deciduous primary foliage. These buds, very similar to axillary buds in D. dorycnioides, may either remain permanently inhibited or grow out into small, gray-pubescent, leafy spurs serving to carry on a limited photosynthesis during the dry winter months. At this stage, D. hemsleyana becomes uncomfortably close to D. dorycnioides, of which it may be no more than a well marked geographic variant in which a seasonal but incomplete loss of pubescence has accompanied a slight increase in leaflet-number synchronized with adaptation to soils poor in lime.

Immediately to the south and east of its range D. hemsleyana is replaced in similar habitats by the similarly glabrous, small-leaved, densely tuberculate D. minutifolia. When flowers are present this is easily distinguished by the relatively loose spike, deciduous bracts, and prominently gland-sprinkled or gland-tipped petals. The two species are contrasted further on Plate CV. The only genuinely sympatric close relative of D. hemsleyana is D. bicolor var. bicolor, variable in vesture and foliage but consistently different in its long, tapering, loosely flowered spikes.

The type-collection of D. hemsleyana is attributed to Parry and Palmer, but it flowers so late in the year that it must have been taken by Palmer alone, after Dr. Parry had returned to the United States (see McVaugh’s Life of Edward Palmer, p. 78). Schaffner’s specimens, collected the same year, are so much like the type, that one is tempted to think they were collected from the same population and on the same day. The isotype at Kew was referred by Hemsley to the then poorly known Baja Californian D. ramosissima Benth (our D. brandegei), which has similarly warty stems but a loose spike and deciduous bracts. When Rose noticed the mistake he dedicated Parosela hemsleyana to the Kew botanist, but explicitly cited the duplicate at US as typus.