Dalea leporina (Aiton) Hemsl.

Authors

Rupert C. Barneby

Authority

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.

Family

Fabaceae

Scientific Name

Dalea leporina (Aiton) Hemsl.

Synonyms

Psoralea leporina Aiton, Parosela leporina (Aiton) Rydb., Dalea leporina (Aiton) Hemsl., Psoralea lagopus Cav., Dalea lagopus (Cav.) Willd., Parosela lagopus Cav., Dalea alopecuroides Willd., Psoralea alopecuroides (Willd.) Poir., Petalostemon alopecuroides (Willd.) Pers., Dalea linnaei Michx., Dalea cliffortiana Willd., Dalea annua var. ebracteata Kuntze, Parosela bigelovii Rydb., Dalea bigelovii (Rydb.) B.L.Turner, Parosela costaricana Rydb., Petalostemum oreophilum Cory, Dalea oreophila (Cory) Cory, Dalea leporina var. alba (Michx. ex Roem.) H.D.Harr., Dalea alba Michx. ex Roem.

Description

Species Description - Erect annual herbs (1.5) 2.5-10, rarely 8-15 dm tall, glabrous to the spikes, when depauperate simple and monocephalous but more often paniculately branching from above, near, or below the middle, the widely or strictly incurved-ascending branches either simple or again branched, the primary axis usually smooth and stramineous at base, becoming green or purplish, striate, and d= sparsely (rarely densely) glandular- verruculose distally, the foliage green, the leaflets smooth above, commonly paler and always punctate beneath; leaf-spurs 0.4-1.6 mm long; stipules subulate, 1-3 mm long, brownish or livid becoming dry and fragile; intrapetiolular glands usually spiculiform; post-petiolular glands hemispherical or mammiform, prominent, pale yellow or orange; leaves 2-9.5 cm long, shortly petioled or subsessile, the rachis narrowly green- margined, sulcate ventrally, the main cauline ones with (8) 10-17 (24), the rameal ones (rarely all of some dwarf individual plants) often only 4-10 pairs of oblanceolate, oblong-oblanceolate, or obovate, emarginate or retuse, exceptionally obtuse leaflets (2) 3-12 mm long, these flat and relatively thin-textured in more mesic habitats, loosely folded, thicker, often red-margined in more xeric ones; spikes terminal to the main axis and all branches, the latter often over-topping the former, pedunculate, the peduncles (1.5) 3-12 (15) cm long, the spike itself moderately dense, narrowly ovoid becoming cylindroid, without petals or androecia 8-12 (15) mm diam, the pilosulous axis finally (0.8) 1.5-7 (10) cm long; bracts all deciduous or the lowest ones subpersistent, ovate to lance-acuminate or abruptly caudate, 2.5-7 mm long, the lowest glabrous or subglabrous and glandular dorsally, the interfloral ones ± pilosulous and ciliolate, the body and tail varying in color from pale green to greenish- or blackish-purple; calyx 3-5.2 (6.5) mm long, thinly to densely pilose-pilosulous from base upward with fine, ascending hairs, the tube (1.7) 2-2.5 (2.8) mm long, recessed behind the banner, the ribs filiform, brown or livid-nigrescent, the intervals membranous, flat or nearly so, charged with 2 ± irregular rows of small orange blister-glands (sometimes confluent into 1 row of ± large elliptic ones), the broadly ovate-triangular and apiculate to lance-acuminate, often but not always gland-spurred teeth 1-2.8 (4) mm long; petals most commonly milky-white to bright bluish-purple or nearly blue, in some races white, all eglandular or the banner rarely gland-tipped, the epistemonous ones perched 1.2-2.8 mm below separation of the short filament-tassel, readily deciduous on expansion; banner (3.4) 4.4-6 mm long, the claw 1.7-3 mm, the ovate and basally angled to oblong-elliptic, erect blade (1.7) 2-3.7 mm long, 1.2-2.4 mm wide; wings (1.6) 1.9-3 mm long, the claw 0.3-0.9 mm, the oblanceolate or oblong- elliptic blade not or obscurely auricled at base, (1.3) 1.6-2.4 mm long, (0.4) 0.50.9 mm wide; keel 2.1-3.1 (3.5) mm long, the claws 0.5-1.1 mm, the blades like those of the wings but sometimes broader and more oblique, 0.7-1 mm wide; androecium 9-10-merous, 5-6.8 mm long, the filaments free for 0.6-1 mm, distally whitish or blue-purple, the connective gland-tipped, the pallid or dark blue anthers (0.2) 0.250.35 (0.4) mm long; pod obliquely obovate in profile, 2.4-3 mm long, the style-base lateral, the filiform, often livid or brownish prow strongly convex-arcuate, the valves hyaline in the lower ¾, thinly papery, pilosulous, and sometimes finely gland-sprinkled around the distal margin, when fully ripe dehiscent through the ventral and distally through the dorsal suture; seed 1.7-2.4 mm long; n = 7 II (Spellenberg, 1973; Mosquin), 2n = 14 (Mosquin). — Collections 248 (xiv).

Distribution and Ecology - A weedy species, found in disturbed soils along highways, at edge of fields, on stream-banks and lake-shores, northward (formerly, now much depleted) on virgin prairie, southward in savanna, arid grassland, thorn-scrub, and open oak- and pine- forest, reaching 2400 m in Durango but mostly lower, locally plentiful over the greater part of interior Mexico (exclusive of Yucatan peninsula) and upland Guatemala; Costa Rica (to be expected in Honduras and Nicaragua); n., e. of the Continental Divide, through New Mexico and trans-Pecos Texas to s.-centr. and s.-e. North Dakota, e. (in scattered stations, mostly riparian) to Minnesota, w.-centr. Indiana, the Mississippi valley in s.-e. Missouri, and centr. Texas (Brown Co.), extending from s. New Mexico w. of the Divide into the Gila basin in centr. and s.-e. Arizona and adjoining Sonora; also disjunctly, along roads, in fields, and in waste places about villages and cities of the arid centr. Andean plateau, at ± 2250-2850 m, in s.-e. Chile (Apurimac and Puno), through Bolivia from Lago Titicaca s.-e. into n.-w. Argentina (Jujuy, Salta, and Tucuman).— Flowering in N. hemisphere August to December, in S. hemisphere February to May.

Discussion

(Plate XLVIII)

The Hare’s-foot Dalea or Terciopelillo ("little velvet") is the most widely dispersed species of its genus. In North America it spans nearly 35° in latitude, and reappears, probably as a denizen of long standing, on the arid plateaux of the interior middle Andes. The species is so well and so widely known that I judge it superfluous to cite representative collections, and will confine my remarks to commentary on intraspecific variation and its repercussion in the synonymy.

The individual plant of D. leporina is an annual of relatively long duration. The seed germinates with the onset of warm weather or, southward, with early summer rainfall, but flower buds do not form until the equinox approaches, and full anthesis is generally delayed until late August or September, continuing, northward, until frost and, southward, until drought rather than frost puts an end to active growth. Accidents of microhabitat and nutrition play large roles in determining stature of the plant, which may be simple and monocephalous, due to abortion of all axillary branchlets, or paniculately branched from near the base or only from well above the middle. The spikes of calyces are usually about one centimeter in diameter, but occasional gigas individuals (e.g. Ripley & Barneby 14095, NY) with spikes up to 1.5 cm thick have been encountered among more ordinary forms. The cauline leaves that develop during the season of long days are relatively elaborate, with many (mostly 10-17) pairs of leaflets; they are commonly drought-deciduous, giving way distally to shorter simpler leaves which develop with the flowers during the season of shorter days and longer nights. A form found in pine forest of the northern Sierra Madre in Mexico and southern New Mexico is characterized by stems uniformly short and slender. It passes directly from the seedling stage to the flowering stage, dispensing with the larger cauline leaves. The extreme phase of this perhaps taxonomically significant form, which was recognized by Rydberg as Parosela bigelovii, may have as few as 5-7 pairs of leaflets in even the larger leaves (cf. Ripley & Barneby 13967, NY), but is linked to the main series by intermediates. Rydberg (1920, p. 68 in key, p. 75) associated (and so contrasted) P. bigelovii not with its really close ally P. leporina but with P. polygonoides, thereby conferring on it a spurious air of distinction. According to Rydberg the calyx of Dalea leporina should differ from that of ser. Polygonoides in its symmetrically cleft tube, but in reality its adaxial sinus, like that of D. polygonoides itself, is always more or less deeply recessed behind the banner. Experimental cultures are needed to determine whether the loss of large cauline leaves in P. bigelovii is genetically or environmentally controlled.

Two other seemingly trivial types of variation were unduly emphasized in Rydberg’s revision: density of lens-like glands on the stems and coloring of the petals and androecium. A phase with relatively many glands, but in no other way different from ordinary Mexican D. leporina, was described as P. costaricana, a negligable segregate. The color- variants have had a longer history.

Over most of its range southward from extreme southwestern United States the petals of D. leporina are blue, but vary in depth of coloring from a pale milky shade to a rich and pure azure or a bluish-lilac, heavily pigmented petals being accompanied normally by dark green leaves and a blue or lurid tassel of filaments, which becomes conspicuous after the early fall of the petals themselves. Northward and northeastward from the latitude of middle New Mexico the petals are normally white or (fresh) faintly blue-tinged, the tassel whitish, and foliage of a brighter, fresher green, as though from a general depletion of anthocyanin. Rydberg’s P. leporina and P. alopecuroides correspond with these southern and northern variants, which are not otherwise perceptibly different, even though they show a fair measure of geographic segregation. In northern Mexico the distinction does not seem viable, for white and blue flowers may occur in one small colony of plants (Ripley & Barneby 14,168, NY) and white petals can surround either a white or a blue tassel. For those who may choose to distinguish the two forms at the infraspecific level there is unfortunately no valid name at present available, the D. leporina var. alba of Harrington, designed for the northern variant, being technically unacceptable. Harrington seems to have taken the synonymy from Rydberg, but failed to note Rydberg’s cautious note of interrogation when he cited D. alba Michx. in the synonymy of Parosela alopecuroides. Rydberg cannot have actually seen the rare pamphlet, a seedlist issued in Zurich by J. J. Roemer, in which D. alba appears merely as a nomen nudum, not attributable with any security to a particular species. Michaux had a few years previously introduced to European gardens not only the annual white-flowered D. leporina, which he (or L. C. Richard) confused with the Dalea of Linnaeus and rechristened D. linnaei, but also the white-flowered perennial Dalea (or Petalostemum) Candida, which may just as easily have been the plant in cultivation in Zurich. Nor can D. leporina alba be taken up as a new name dating from Harrington’s Flora of Colorado (1954), for it lacks there a validating diagnosis.

The confusion between Dalea leporina and D. cliffortiana which lasted from Michaux to modern times, even though the two entities were explicitly separated by Willdenow, has been recounted elsewhere (Barneby, 1965). The first dissent is found in Kunze’s Revisio Generum, where they were distinguished at varietal level, the D. annua ebracteata, listed above, being separated from genuine D. annua (= our D. cliffortiana) by its deciduous interfloral bracts.

Attention must be drawn to my reinterpretation of Psoralea lagopus Cav. which Rydberg, not having seen the type, misunderstood, transferring the name (as Parosela lagopus) to the related species treated below as D. exserta. It is a curious coincidence that Aiton and Cavanilles should have invented, almost simultaneously, for the same species independently introduced to cultivation in London and Madrid, epithets so similar in meaning as leporina and lagopus. However, the softly silky spike of calyces, to which the tiny evanescent petals contribute little in the way of ornament, is obviously the feature that first strikes the eye. The vernacular terciopelillo, recorded by Cavanilles and still current on the Mexican plateau, has a cognate origin.

The synonym D. pedunculata Pursh, confidently referred by Rydberg to the synonymy of P. alopecuroides, is mentioned in this account as unidentified (Appendix I).

All of the foregoing remarks refer to D. leporina as found in North America. The Andean populations are less well documented by herbarium material, but we have enough to know that although less variable overall than those of Mexico they are not homomorphous. The calyx-teeth, for example, vary in length, just as northward. In Bolivia the lowermost bracts tend to be relatively long-tailed, and the glands in the calyx-membranes are more often than elsewhere confluent into a vertical row of 2-3 narrowly elliptic lenses. However the latitude of variation lies entirely within that already recognized in Mexican races of the species, and it seems rational to suppose that D. leporina is not aboriginally native in the southern hemisphere. The earliest record that I have seen is that of Pearce, who collected specimens "in cultis" at Tarija in 1864. All stations since recorded lie on or near the main Andean highway that runs from Abancay in Peru by way of Cuzco, Sicuani, La Paz, Oruro, Sucre, and Tarija into northwestern Argentina. Burkart (1952, p. 253, as D. alopecuroides) accepts the species as native in Argentina, but taking into account the weedy potential of D. leporina amply documented in North America and the fact that all other members of subgenus Dalea are confined to the northern hemisphere, its disjunct Andean range seems to be of adventive nature. One collection from Cochabamba, Bolivia (Buchtien 2383) has been distributed under an unpublished name ("lucidocarpa") attributed to H. H. Rusby. The plants (NY, US) are in advanced fruit and interesting because they clearly show the dehiscence of the pod by separation of the valves along the adaxial suture.

Beyond the range described above, D. leporina has appeared as a fleeting ruderal near New York and in coastal Massachusetts (Snyder, Rhodora 52: 299. 1950), but is not known to have become established in the Atlantic states.

The holotypus of Petalostemon oreophilum could not be located in 1975 at the Gray Herbarium, where Cory stated that he had placed it. A specimen of D. leporina preserved there under an unpublished trinomial (Petalostemon oreophilum var.) was collected in Limpia Canyon n.-e. of Fort Davis 28 September 1942 (Cory, s. n.) and was perhaps deposited at GH by mistake.

Distribution

North Dakota United States of America North America| Minnesota United States of America North America| Indiana United States of America North America| Mississippi United States of America North America| Missouri United States of America North America| Texas United States of America North America| Arizona United States of America North America| Sonora Mexico North America| Mexico North America| Chile South America| Apurímac Peru South America| Puno Peru South America| Bolivia South America| Argentina South America| Jujuy Argentina South America| Salta Argentina South America| Tucuman Argentina South America| Peru South America|