Dalea filiciformis
Rupert C. Barneby
1. Dalea filiciformis Robinson & Greenman
(Plate XXIX)
Herbaceous, suffruticose, or (southward) becoming shrubby and up to 2 m tall, when herbaceous the stems rarely over 5 dm long, dying back yearly to the crown of a taproot up to 3 cm diam, when shrubby effusely branching and broomlike, glabrous to the pedicels, the young stems purplish or glaucescent, densely micro-tuberculate, the old wood gray and furrowed, the foliage greenish-glaucescent, the thick-textured leaflets dotted or pustular beneath; leaf-spurs 0.2-1 mm long; stipules narrowly subulate, livid, 0.3-1.5 mm long, deciduous; intrapetiolular glands 0 or minute, impressed; post-petiolular glands small, impressed or scarcely prominent; main cauline leaves 1.5-4 (4.5) cm long, shortly petioled or subsessile, with subterete, narrowly grooved, punctate rachis and (11) 13-29 orbicular, ovate, broadly oblong-ovate, or cordate, emarginate or very obtuse, flat leaflets 1-3 mm long; peduncles leaf-opposed and terminal to the main stem and (when present) some lateral branches, (1) 2-12 cm long; spikes racemiform, always laxly often remotely (5) 8-20-flowered, the flowers ascending on erect, hirsutulous pedicels 0.6-1.2 mm long, the glabrous axis becoming 3 - 20 ( 27) cm long, the flowers elevated well beyond the leafy parts of the stem; bracts broadly ovate-acuminate, spathaceous, submembranous, wrapped around the young flower-buds but thrown off long before anthesis, commonly livid or purplish about the obscure keel, brownish or pallid toward the margins, glabrous and gland-sprinkled dorsally, glabrous within, sometimes minutely puberulent at tip; calyx jointed to the pedicel, deciduous with the pod, 6.7-10 mm long, a little accrescent after early anthesis, hirsute with straight, lustrous, spiral hairs up to 1-1.8 mm long, the shallow tube 2.2-3 mm long, a little oblique at mouth, the ribs prominent, often purplish, the submembranous intervals charged with 3-5 uniseriate, orange or livid blister- glands, the narrowly lance-acuminate or -caudate, 1-2 (3)-spurred, plumose teeth unequal, the dorsal one longest, (3.7) 4-7.6 mm long, all ± stellate in age; petals concolorous or nearly so, commonly opening dull pinkish-purple or lavender, drying brownish or livid, rarely soft blue drying brown, all coarsely many-veined (the veins branching distally), the blade of the banner gland-sprinkled, those of wings and keel glandless (or the latter with a few small glands on blade, or one at apex, or both), the inner ones elevated only 0.5-1.5 mm above the hypanthium; banner 4.1-6.2 mm long, the claw (1.5) 1.8-2.5 mm, the spade-shaped, commonly acute blade open at base, 3-4.6 mm long, 2.8-4 mm wide; wings 5.1-6.6 mm long, the claw 1.5-2 mm, the obliquely ovate, obtuse blade 3.6-5 mm long, 2.2-3.6 mm wide; keel 7.3-11.3 mm long, the claws 2.6-3.3 mm, the broadly ovate-elliptic blades (4.8) 5.2-8.8 mm long, (3) 3.2-5 mm wide; androecium (6.6) 7.5-10 mm long, the longest filament free for (2.9) 3.2-4 mm, the bluish, gland-tipped anthers 1-1.35 mm long; pod harp-shaped, strongly compressed, 3-3.5 mm long, the style-base lateral or latero-terminal, the dorsal keel slender but distally prominent, the valves submembranous and glabrous proximally, papery and hirsute distally, charged with blister-glands arranged in 2 oblique crescents; seed ± 2.6 mm long; 2n = ±8 II (Mosquin). — Collections: 40 (xi).Arid grassy flats, gullied knolls and barren, eroded hillsides, sometimes in crevices of cliffs or shelving rock-faces, 1410-2210 m (± 4700-7370 ft), on a variety of soils but mostly on gypsum and limestone, less often on mixed alluvia, volcanic ash, and perhaps other porous soils, local but widespread over the arid lands of the Mexican Plateau from Galeana district in the Sierra Madre Oriental, Nuevo Leon, to s.-e. Durango, s. to the Valley of Mexico (Estado and Distrito Federal), and through the desert valleys of Puebla and adjoining Morelos to n. and centr. Oaxaca. — Flowering May to October, and (southward) well into winter .—Representative: Nuevo Leon: C. & M. Mueller 530 (F, GH, MEXU, TEX). San Luis Potosi: Ripley & Barneby 13,296 (CAS, GH, K, MEXU, MICH, NY, UC, US). Durango: Ripley & Barneby 14,163 (NY). Aguas Calientes: Rose & Painter 7706 (F, NY, US). Guanajuato: Ripley & Barneby 13,379a (NY). Hidalgo: Rose & Painter 7108, 8315 (NY, US). Mexico (D.F.): Pringle 8522 (F, GH, M, MEXU, NY, UC, US, Z). Mexico (Edo.): Rzedowski 16,791 (MEXU, TEX). Morelos: Ripley & Barneby 13,704 (CAS, NY, US). Puebla: Purpus 1204 (F, NY, UC); Ripley & Barneby 14,569 (CAS, NY, US). Oaxaca: Ripley & Barneby 13,655 (CAS, K, MEXU, MICH, NY, US), 14,659 (CAS, F, MEXU, MICH, NY, UC).
Dalea filiciformis (fern-shaped, presumably of the leaves, perhaps likened to the fronds of some Pellaea) Robins. & Greenm., Proc. Amer. Acad. 29: 382. 1894. — "Collected upon limestone hills, Villar, San Luis Potosi [ = Puerto de San Jose, a railroad halt on the Tampico line ± 50 mi n.-e. of San Luis Potosi], 14 September, 1893 (no. .5472)." — Holotypus, collected by C. G. Pringle, GH! — Parosela filiciformis (Robins. & Greenm.) Rose, Contrib. U. S. Nat. Herb. 8: 303. 1905.
It seems almost superfluous to stress the unique facies of D. filiciformis, recognized on sight by the loose raceme of long-toothed, silvery-plumose calyces carried up on leaf- opposed peduncles well beyond the neat glaucescent foliage. The species has no really close relative in Dalea and its affinities are difficult to estimate. Rydberg placed it in his subgen. Trichopodium sect. Calycosae, next to the shrubby but yellow-flowered Parosela berlandieri (= D. melantha var. berlandieri) and D. calycosa, which is a species of Marina. These three have in common pedicelled flowers but little else. The detached flower of D. filiciformis resembles that of D. formosa and D. purpusi in the proportions and vesture of the calyx, but the nervature of the petals, the long pedicels, and the spathaceous bracts are very different. The harp-shaped pod of D. filiciformis, charged with two oblique crescents of blister-glands, recalls that of several species of Marina, from which it must be excluded, however, by the presence of two collateral ovules, leaflets lacking oblique lineoles, and hairs of the spiral, finally fulvescent type. The pedicelled flower combined with a sometimes frutescent habit and petals traversed by many thick, distally branching veins are suggestive of Psorothamnus, but the inner petals are elevated about the hypanthium on a definite even though short column, and neither bracts nor pod fit comfortably into the latter genus. Mosquin has found in one collection of D. filiciformis approximately 8 pairs or chromosomes, the number found in all members of sect. Theodora. Because of their dense spikes of finally nodding flowers these differ greatly in appearance. However, the spathaceous, submembranous, hairless bracts wrapped around the flower-buds of D. filiciformis are most nearly matched in the small sect. Lachnostachyae which are closely related, despite a basic chromosome number of seven, to eight-paired sect. Theodora. I suspect that these three groups, Theodora, Lachnostachyae, and Psoropteris, all of which are adapted to extremely xerophytic conditions that I have postulated as the primitive environment in which the ancestors of daleoid legumes differentiated, are related but primitive types of ancient lineage. The appearance in D. filiciformis of some characters suggestive of Psorothamnus and Marina supports the view that it is a primitive relic.
North of the Neovolcanic Belt D. filiciformis is encountered most commonly on gypsum-flats and on gullied gypseous hills and bajadas in the zone of arid grassland. It is not, however, the obligate gypsophyte, as suggested by Johnston (Jour. Arnold Arb. 22: 159. 1942), for I have collected specimens from crevices of hard, crystalline limestone in the Sierra de Guadalcazar, San Luis Potosi, and on pebbly alluvia, possibly saline but not obviously gypseous, in Durango and Guanajuato. In Puebla and Oaxaca the species occurs on a variety of sedimentary and volcanic substrates, and appears equally at home on brushy hillsides, highway embankments, terraces of chalky volcanic ash, and basalt cliff-ledges, although always preferring open sites and most abundant in climax grassland.
The populations of the species found in the Valley of Mexico and northward are alike in being herbaceous or only feebly suffrutescent. Normally the stems arise anew each summer from the crown of a disproportionately thick taproot that may reach a diameter of 3 cm. Each stem gives rise to one or two, rarely more numerous, very long spikes that rise much beyond the leafy part of the plant and account for half or more of its total stature of 3-7 dm. The leaflets of main cauline leaves are 8-14 (exceptionally 17, not as described in the protolog, up to 37) pairs and the petals open rose- or lavender-purple, fading brownish or livid-purple. In Puebla, Morelos, and Oaxaca, the plants flower first as herbs but the stems persist or tend to do so and may ultimately form broomlike bushes with pliant but woody stems up to 2 m tall. With increased stature the leaflet number falls to about 7-10 pairs, the peduncles and racemes tend to be shorter, and the flowers become on the average a little smaller. Color of the petals is quite variable southward; perhaps most commonly pinkish striped with brown veins, but sometimes clear blue veined with blue of darker shades. Johnston (1941) thought the southern plant probably distinct from typical D. filiciformis, but the much more abundant material now at hand shows that the supposed differences are not firmly linked with each other or with patterns of dispersal.
Considering that D. filiciformis grew (at least formerly) as near to the heart of Mexico City as the castle hill at Chapultepec and the suburban village of Santa Fe, and was in fact first collected as early as 1791, somewhere in southern Mexico, by Tadeusz Hänke, it is remarkable that it remained undescribed until Pringle rediscovered it, in 1893, in San Luis Potosi. In any case I have been unable to identify it with any of several, as yet obscure species described during the XIX century and based on types that have been mislaid, lost, or destroyed.
References: [Article] Barneby, Rupert C. 1977. Daleae Imagines, an illustrated revision of Errazurizia Philippi, Psorothamnus Rydberg, Marine Liebmann, and Dalea Lucanus emen. Barneby, including all species of Leguminosae tribe Amorpheae Borissova ever referred to Dalea. Mem. New York Bot. Gard. 27: 1-892.Multimedia:
