Dalea zimapanica

  • Title

    Dalea zimapanica

  • Author(s)

    Rupert C. Barneby

  • Scientific Name

    Dalea zimapanica S.Schauer

  • Description

    137.  Dalea zimapanica Schauer

    (Plate CXXIV)

    Slender shrubs up to 2.5 m tall, sometimes flowering precociously when feebly suffruticose and only 0.5 m tall, usually becoming bushy and many-stemmed, or finally subarborescent, commonly glabrous to the inflorescence but the young branchlets and foliage sometimes pilosulous with sparse spreading hairs, the young stems castaneous, purplish, or rarely stramineous, smooth or thinly verruculose distally, each major cauline axis virgate below, paniculately branched distally, each branchlet terminating in a short, densely silky-pilose spike of calyces, the whole inflorescence broadly corymbose; leaf-spurs 0.2-0.9 mm long; stipules subulate, often livid or castaneous, 0.4-1.6 mm long; intrapetiolular gland conic; post-petiolular glands larger, prominent; leaves subsessile or very short-petioled, the primary cauline ones 2-4.5 (5) cm long, with margined rachis and 7-12 (15) pairs of oblong, elliptic-oblong, or obovate, emarginate to gland-apiculate, thick-textured, flat or navicular leaflets 2-6(7) mm long, the leaves of the upper branchlets (sometimes of all present at anthesis) shorter, with as few as 4-8 pairs of generally smaller leaflets, all green above, paler or glaucescent and prominently gland-dotted beneath; peduncles 0.3-3.5 (4.5) cm long, the early ones always well-developed, the later short but usually evident, only the ultimate and smallest heads of each division of the panicle sessile or almost so; spikes moderately dense, ovoid-conical becoming subglobose or the larger ones shortly oblong-cylindroid, without petals 10-13 mm diam, the densely pilosulous axis 3-18 (25) mm long; bracts

    deciduous, lanceolate, 2-5.5 mm long, castaneous or pallid at base, green, livid, or purplish distally, gross-glandular dorsally, the lowest, sometimes all, glabrous on back, but always ciliolate below middle, the rest usually pilosulous dorsally to middle, thence glabrate; calyx (4.1) 4.5-7.7 mm long, densely pilose with ascending, at length widely spreading, golden hairs up to (0.7) 0.8-1.35 mm long, the tube (2.1) 2.2-2.6 mm long, the salient ribs brownish, the membranous intervals charged with 1 (sometimes irregular) row of yellowish glands, the teeth subulate-aristate from a deltate-triangular base, unequal, the dorsal ones longest, (2) 2.3-5.3, mostly 3-4 mm long, hence longer (rarely to 0.2 mm shorter) than tube, all gland-spurred, plumose, stellately spreading in fruit; petals yellow or greenish-yellow edged with red or reddish-brown, all or at least the keel and wing-tips fading dull purple, all charged at apex with a large, linear- elliptic gland, the blade of banner sometimes sparsely gland-sprinkled, the epistemonous petals perched low on the androecium (± 1.1-1.7 mm above hypanthium; banner (4.2) 4.6-6.8 mm long, the claw (1.7) 2-3.2 mm, the deltate-cordate blade (2.4) 2.6-4 mm long, 2.6-3.8 mm wide, the small basal lobes incurved and adherent, forming lateral pockets; wings 4.9-7.1 mm long, the claws 1.3-2.1 mm, the broadly lance-oblong blades 3.6-5.6 mm long, 1.8-3 mm wide; keel (6.2) 7-8.8 mm long, the claws (2) 2.4-3.5 mm, the obliquely ovate blades (4.6) 4.8-6 mm long, 2.6-3.5 mm wide; androecium 10-merous, (6) 6.5-8.3 mm long, free for up to 1.7-2.2 mm, the connective gland-tipped, the anthers 0.65-0.8 mm long, the alternate ones sometimes much smaller; pod triangular in profile, 2.4-2.7 mm long, the style at comer, the prow slender but salient, the valves hyaline in lower thence thinly papery, gland-sprinkled, and densely pilosulous distally; seed 1.6-1.8 mm long. — Collections: 58 (ix).

    Dry hills and terraces of barrancas, becoming abundant on over-grazed and gullied grassland, mostly between 1650 and 2700 m, common on the plateau from Valley of Mexico (Distrito Federal and adjoining Estado) e. through Tlaxcala and centr. Puebla just into Veracruz (descending in valley of Orizaba to 1200 m), s. in Mexico to the margins of Balsas Depression, not recorded from Morelos, but again common s.-ward in Puebla to Tehuacan desert and through the foothills of Mixteca Alta to the valley of Oaxaca. — Flowering September to January. —Representative: Mexico. Distrito Federal: Bourgeau 327 (F, L, M, NY, P); Pringle 9078 (F, GH, K, NY); Purpus 5652 (F, NY, UC); Ripley & Barneby 14,911 (CAS, DAO, NY, US). Naucalpan: Bolahos 2550 (ENCB); Huixquilucan: Rzedowski 21,526 (ENCB); Pringle 4325 (BR, F, GH, K, NY, UC, W, Z). Villa Guerrero: Matuda 27,893 (NY). Ixtapan de la Sal: Matuda 27,430 (NY). Ixtapaluca: Matuda 18,593 (NY). Tlaxcala. Calpulalapam: Ripley & Barneby 13,633 (CAS, NY, MEXU, US). Tlaxcala: Ripley & Barneby 13,635 (CAS, NY, MEXU). Puebla. Puebla: Arsene 1201 (US). Tepeaca: Arsene 3596 (BR, L, NY, Z). Amozoc: Arsene 1907 (BR, NY). Cholula: Nicolas in 1902 (BR, F, L, Z). Tehuacan: Purpus 5648 (F, NY, UC). Veracruz. Acultzingo: Ripley & Barneby 14,743 (CAS, NY, US). Orizaba: Arsene 1667 (L). Oaxaca. Huajuapan de Leon: Ripley & Barneby 13,652 (CAS, NY, US). Teposcolula: Seler 1553 (US). Etla: Conzatti 2044 (F). Ixtlan de Juarez: Gentry 12,064 (MEXU, RENNER). Mitla: Ripley & Barneby 14,617 (NY). Miahuatlan: Ripley & Barneby 14,630 (CAS, MEXU, MICH, NY, US).

    Dalea zimapanica (of Zimapan, Hidalgo, but not now known there) Schauer, Linnaea 20: 746. 1847.— "In circuitu urbis Zimapan in Mexico. Aschb. n. 460." — Holotypus, formerly B, not seen, but the protologue decisive. — Parosela zimapanica (Schauer) Rydb., N. Amer. Fl. 24: 109. 1920.

    (?) Dalea lanata (woolly, of the spikes) G. Don, Gen. Hist. Diehl. Pl. 2: 224. 1832. — "Native of Mexico." — Holotypus, formerly herb. Lambert., not known to survive. Non D. lanata Spreng., 1826.

    Psoralea luteola (yellowish) S. & M., Pl. Nov. Hisp. 121. 1889. — "Habitat in Sancti Angeli oppido ad rivulorum margines." — Presumed isotypus, "Dalea luteola misit Pavon 1827", P! potentially isotypic are Herb. S. & M. 2666 p. p., F, MA! and "Dalea lutescens sp. nov. de Mexico", probably ex herb. Lambert, but not annotated by G. Don, OXF! (this conceivably holotypus of D. lanata G. Don).

    Parosela diversicolor (of different hue) Rydb., N. Amer. Fl. 24: 109. 1920.— "Type collected in Sierra de Clavellinas, State of Oaxaca, October 1894, Charles L. Smith 549..."—Holotypus, US! isotypus, NY!

    Except in southern Puebla and Oaxaca, where its range coincides with that of D. carthagenensis var. capitulata, this is the only member of ser. Thyrsiflorae found in arid interior southern Mexico; it is readily recognized by the shrubby habit, many small leaflets of thick texture, repeatedly branching, finally corymbose inflorescence of many subcapitate spikes, and yellow petals tinged with red around the exterior margins and tipped with large elliptic or crescentic blister-glands. The var. capitulata differs in its fewer leaflets, of primary cauline leaves 4-8 not 7-12 or 15 pairs, and in the spicate-thyrsiform arrangement of the flower-heads. The petals open creamy or greenish-creamy rather than the rich yellow of D. zimapanica, but fade a similar dull pinkish-brown or maroon purple. Other shrubby, yellow-flowered daleas of the region have longer flower-spikes, or (D. lutea) persistent interfloral bracts, or (D. melantha) much fewer leaflets, or some combination of these differences.

    Rydberg (1920, p. 109) described D. zimapanica as glabrous below the flower-spikes, and this is true of the majority of populations known in the valley of Mexico. Occasionally, however, young branchlets and upper leaves, rarely all leaves, are thinly puberulent, but these occur sporadically, sometimes near the glabrous form (as at Ixtapan de la Sal, Ripley & Barneby 13,765, 13,757, NY). An extreme form from Sierra Madre del Sur in Oaxaca (near Miahuatlan, cited above) has both stems and foliage pilosulous with widely spreading hairs up to 0.3-0.4 mm long. These plants are further unusual in having short calyx-teeth (2-2.7 mm), plumose with relatively short hairs; but the variation is of a sort to be expected among the polymorphic and unstable Thyrsiflorae and is not considered taxonomically significant. The petals of D. zimapanica vary somewhat in size, but the typus of supposedly large-flowered P. diversicolor can be matched in this respect by material from the Valley of Mexico; it seems to represent nothing more than a vigorous and showy minor variant.

    A notable individual plant (s. of Matatlan, at s. end of vale of Oaxaca, Ripley & Barneby 14,618, CAS, NY), found growing among prolific thickets of D. zimapanica and D. leucosericea, is thought to be a hybrid between these associated but not closely related species. The foliage of the hybrid is intermediate in leaflet-number (4-6 pairs) and is pubescent with a thin soft vesture suggesting that of D. leucosericea but thinner; and the yellow, finally reddish-brown flowers are almost those of D. zimapanica but are disposed in relatively long and loose spikes.

    The nomenclature and synonymy of D. zimapanica are clouded by the destruction or dispersal of type-specimens. The original collection of Aschenborn is presumed lost in the Berlin disaster, but Schauer’s protologue is precise and detailed, leaving little room for doubt as to his intentions. It is disturbing only in so far that the species was not encountered near Zimapan (or elsewhere in Hidalgo) by other early botanists who visited this well-botanized locality, and has been sought there vainly in recent years. The identity of Psoralea luteola appears firmly established by means of the original description and by coincidental existence (even though only tenuous proved connection with) specimens in the Sesse herbarium and others distributed, probably from the same source, by Pavon. Due to brevity of the protologue, doubt remains as to the application of D. lanata G. Don, but as this is a later homonym, the problem is academic. The plant at OXF labelled Dalea lutescens sp. nov. de Mexico, which is mounted in the style of others known to have been part of the Lambert herbarium, is a good even though unprovable candidate for the missing typus of D. lanata, but the discrepancy in epithets (lutescens seems a likely variant of luteola, found in a Pavon specimen at P) cannot be explained.