Dalea dorycnioides

  • Title

    Dalea dorycnioides

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Dalea dorycnioides DC.

  • Description

    106.  Dalea dorycnioides DeCandolle

    (Plate XCVIII)

    Small, twiggily branching, polypodial shrubs of bushy outline, at anthesis (1.5) 3-10 (12) dm tall, with smooth or furrowed, brown bark and densely, grossly verrucu- lose young branches, the growth of the year ± densely silky- or velvety-pilosulous or -tomentulose with fine spreading-ascending hairs up to 0.1-0.4 mm long, the stems sometimes glabrescent, castaneous or livid, the foliage as a rule gray or silvery, the leaflets mostly pubescent both sides, sometimes glabrescent or even glabrous above, then greenish, exceptionally green both sides but always bearing some rudiments of vesture, and the young spurs always densely pubescent, the leaflets punctate on both sides, but the dots commonly concealed by vesture; leaf-spurs 0.3-1.1 mm long; stipules triangular or subulate, livid or castaneous, puberulent or glabrate, 0.6-2 mm long; intrapetiolular glands minute, impressed, often concealed by vesture; post- petiolular glands conic or mammiform, prominent, orange or transparent, glabrous or puberulent; main cauline leaves (3) 4-16 (24) mm long, short-petioled or subsessile, with narrowly margined, often punctate rachis and 2-4 pairs of obovate or obovate- cuneate to broadly oblanceolate, truncate-emarginate or retuse, usually folded, sub- sessile or shortly petiolulate leaflets (1) 2-7.5 (12) mm long; peduncles terminal to all the branchlets (the first one of each main branch leaf-opposed), 0-3.5 (7) cm long; spikes very dense, conelike, conic-ovoid or depressed-hemispherical becoming subglobose or shortly oblong, without petals or androecia 7-9.5 mm diam, the villosulous axis 2-12 (20, exceptionally a few up to 30) mm long; bracts persistent, broadly rhombic-obdeltate, -obovate, or flabellate, abruptly short-acuminate or truncate and mucronate, shallowly concave, (1) 1.5-2.5 mm long, the outermost sometimes shorter than the rest, all pilosulous and tuberculate dorsally or glabrescent and castaneous in the distal third, except at very tip silky within; calyx (3.4) 3.8-5.3 mm long, densely silky-pilosulous with spreading-ascending or subappressed hairs up to it: 0.2-0.6 mm long, the ovoid, often oblique tube 2.2-3.4 mm long, recessed behind the banner, the ribs slender, immersed or scarcely prominent in age, the rather firm but pale intervals charged with one row of usually 3-4 very small, transparent glands visible only from within, the triangular-subulate, reddish or livid, gland-spurred, internally pilosulous, finally connivent teeth unequal, the dorsal one longest, 1.2-2 mm long, obviously shorter than the tube, the ventral pair similar but shorter; petals bicolored, the banner at early anthesis cream-yellow or almost white except for a green eye in the blade, rubescent in age, the inner petals vivid rose-purple or rarely violet-purple, elevated 1.2-2.5 mm above hypanthium rim, all glandless, or either keel or banner or both charged at apex with a small blister-gland; banner 4.5-6.7 mm long, the claw 2.1-3.4 mm long, the little recurved, ovate-deltate, emarginate, hooded blade closed at base into a deep comet, (2.3) 2.9-4 mm long, 2.8-4.2 mm wide; wings 5-7.1 mm long, the claw 1.4-2.5 mm, the broadly oval or lance-oblong blade 3.6-5.7 mm long, 1.33 mm wide; keel 6.6-9.2 mm long, the claws 2.3-4.3 mm, the blades 4.3-6.4 mm long, 2.5-4.4 mm wide; androecium 10-merous, 7.5-9.5 mm long, the longest filament free for ± 2.3-3 mm, the yellowish anthers 0.6-0.8 mm long; n = 7 II (Spellenberg, 1973). — Collections: 30 (viii).

    Dry open brushy and rocky hillsides, stony washes, sometimes abundant on gullied badlands, 1230-2400 m (4100-8000 ft), often forming extensive colonies, in Larrea desert, cactus-thorn-forest, pine-pinyon woodland, or (s.-ward) ascending into pine- oak forest, strongly (perhaps obligately) calciphile, widespread along the w. slope and dry intermontane valleys of Sierra Madre Oriental from s.-centr. Nuevo Leon (Galeana district) to Hidalgo and perhaps extreme n. Mexico, w. to the margin of Mapimi basin in the extreme s.-e. angle of Chihuahua and the lower basin of Rio Nazas in n.-e. Durango; apparently isolated in n.-centr. Oaxaca. — Flowering (August) September - December. — Representative: Chihuahua: Chiang et al 9040 (NY). Durango: Spellenberg & Dunford 2934 (NY); Gentry 6890 (F, NY); Ripley & Barneby 13,590 (CAS, GH, K, MICH, MEXU, NY, US), 14,208 (CAS, NY). Nuevo Leon: Ripley & Barneby 13,793 (NY). Tamaulipas: Gentry 6750 (ARIZ, UC, US); Stanford, Wetherford & Northcraft 880a (ARIZ, NY). San Luis Potosi: Parry & Palmer 148 (BR, NY, US in part); Ripley & Barneby 13,774 (CAS, MEXU, NY, US), 14,763 (CAS, NY, US). Hidalgo: Pringle 8722 (F, M, MEXU, NY, UC, US, W); Purpus 478 (UC). Oaxaca: E. W. Nelson 1916 (NY); Ripley & Barneby 13,670 (CAS, GH, K, MEXU, MICH, NY, US).

    Dalea dorycnioides (resembling some sp. of Dorycnium L.) DC., Prod. 2: 245. 1825.— "...in America calid...(v.s.)"— Holotypus, "ex herb. Thibaud.", G-DC! —Parosela dorycnioides (DC.) Rydb., N. Amer. Fl. 24: 90. 1920 ("dorycnoides").

    Dalea pulchella (pretty) Moric., Pl. Nouv. Amer. 9, Tab. VII. 1836. — "Hab. circa St. Louis de Potosi." —Lectotypus, Berlandier 2202, collected in November, 1830, G! isotypus, NY!— Parosela pulchella (Moric.) A. Heller, Cat. N. Amer. PL, Ed 2: 6. 1900.— Non Dalea pulchella G. Don (1832).

    Dalea decora (handsome) Schauer, Linnaea 20: 743. 1847.— "In Mexici provincia Oaxacana. Aschb. [= Aschenborn] n. 255 et 270."— Typus formerly at B, destroyed in 1943. The ample and detailed description identifies it. — Parosela decora (Schauer) Rydb., N. Amer. Fl. 24: 90. 1920.

    The characters to which D. dorycnioides owes its distinct facies and specific status apart from the polymorphic D. bicolor are the dense, knoblike flower-spikes, ideally depressed-hemispherical to shortly oblong-ovoid, and the broad, short bracts that persist between the calyces until, with ripening of the seed, the inflorescence starts to fall apart. The foliage varies in amplitude and pubescence in ways that can be matched, step for step, in D. bicolor, and there seems to be no way of telling the two species apart until the spikes have taken form. From one end of the species’ range to the other, but especially under conditions approximating desert, the foliage is permanently gray or when young silvery with a close, plushlike indumentum of extremely fine and short hairs; and the leaflets tend to be small (2-6 mm long), crowded on the rachis, and borne on petiolules immersed in the vesture so that they appear nearly sessile. But even in desert, as about Yerbaniz in northeastern Durango, the upper leaf-surface is sometimes green and glabrous. The two known collections from Oaxaca have exceptionally small leaves combined with low stature and small flowers, and one of them (E. W. Nelson 1916, NY) seems to have provided the key characters ascribed to Parosela decora in Rydberg’s monograph. Discounting, for the moment, the chance that I am misapplying the name D. decora, of which the type is lost, I feel sure that the Oaxacan plant that has been associated with the latter name represents a mere form of D. dorycnioides, The closest match for the Oaxacan type occurs, rather unexpectedly, at the northern limit of the species in Nuevo Leon (Galeana district).

    In northern Hidalgo, under relatively mesic conditions of oak-pine forest, but still on limestone, D. dorycnioides is represented by a form with ample primary cauline leaves. The leaflets here are green, large (to 12 mm long), visibly petiolulate, glabrous or nearly so above and only thinly pilosulous beneath. However these green leaves subtend leaf- spurs or buds as densely tomentulose as those of the whiter, desert phase. The typus of D. dorycnioides represents the greener phase, which is often further distinguished by relatively long-pedunculate heads; that of D. pulchella Moric. (non G. Don) the gray-tomentulose, xeromorphic one with mostly sessile or subsessile spikes.

    While I have emphasized the diagnostic importance of the short spike, the close observer will find here and there, even in seemingly uniform populations of normal and typical D. dorycnioides, some individual plants in which the flower-head that terminates each main division of the panicle (and therefore appears leaf-opposed) is, in reality, more or less elongate, and such spikes (e.g. Shreve 9340, ARIZ, with axis up to 3 cm long) isolated from their context suggest direct passage into D. bicolor. Near Zimapan, Hidalgo, where D. dorycnioides is dominant over hundreds of acres of barren, eroded, limestone hills, I found it directly associated with a form of var. bicolor, but even though occasional long spikes were found in dorycnioides-like plants there was no convincing evidence that introgression was taking place between the two species, at least on any significant scale.

    I have seen one old specimen attributed to W. F. Keerl (BR, dated 1829) that is labelled Tlalpujahua, i. e. the gold-mining community near El Oro on the Michoacan-Mexico state line northwest of Toluca. This locality is situated in the Neovolcanic belt, where D. dorycnioides is not to be expected, and the record requires confirmation. The seeds from which the typus of Dalea versicolor Zucc. were raised in Munich were also said to have been collected by Keerl at Tlalpujahua, although the species has not since been seen north of central Oaxaca. The data are thus doubly suspect.

    The epithets decora and pulchella which have been applied to forms of D. dorycnioides are well deserved, for there are few handsomer small shrubs. The neat bushy habit and gray foliage are attractive throughout the year, and the long succession of proportionately large vivid flowers, coming as they do at a season when there are few competitors for attention, entitle the species to garden trial in Mediterranean climates: