Dalea urceolata

Rupert C. Barneby

29. Dalea urceolata Greene

(Plate XLIX)

Slender annual herbs, resembling D. leporina in habit, glabrous to the spikes (except for a few hairs high on the peduncle), the stems commonly purplish at base, distally green or stramineous and charged with a few small prominent glands, either branching from near base and the lateral branches then incurved-ascending and often surpassing the central axis, or simple below middle and few-branching upward, all the more vigorous stems and branches monocephalous, the foliage green above, pallid or glaucescent and punctate beneath; stipular spurs up to 1 mm long, the blades triangular-subulate, 0.7-1.7 (2) mm long; intrapetiolular glands setiform, sometimes minute, brown or livid; post-petiolular glands small but prominent; leaves 1.5-7 cm long, subsessile or very shortly petioled, with narrowly winged rachis and (3) 5-14 pairs of petiolulate, oblong-oblanceolate, very obtuse to emarginate or retuse leaflets 2.5—9.5 mm long; peduncles 0.5-7.5 (12) cm long; spikes ovoid-oblong, the larger becoming cylindroid, without petals or androecia ± 9-10.5 mm diam, the thinly pilosulous or glabrate axis becoming 0.8-4 (5) cm long; bracts dimorphic, the lowest 2-3 larger, firmer, and more persistent than the rest, the interfloral ones deciduous, broadly ovate -acuminate or -caudate, 2-5 mm long, all glabrous, pallid or livid except for membranous margin, ± gland-dotted dorsally, the body either a little longer or shorter than the tail; calyx sessile, before anthesis campanulate, during anthesis becoming ovoid-ellipsoid, a little constricted at the mouth, 3.5-6 mm long, the externally glabrous tube (2.4) 2.6-3.4, in fruit sometimes up to 4.5 mm long, deeply recessed behind the banner, the subfiliform but prominent ribs usually livid, the intervals hyaline, glossy, charged with 1 row of large, oblong-elliptic, orange glands, the teeth triangular or deltate-cuspidate to triangular-acuminate, ciliate like the adaxial sinus with soft, rufescent hairs, pilosulous within, the ventral pair 0.7-2.4 mm long, the rest commonly a trifle shorter; petals 1-3, pale blue to milky white, eglandular, the epistemonous pair, when present, perched near middle of androecium; banner 3.8-5.5 mm long, spatulate, the ovate-elliptic or -subcordate, nearly erect blade 2.2-2.8 mm long, 1.4-2.2 mm wide; inner petals 1.4-2.2 (2.6) mm long, subsymmetrically oblanceolate, very shortly clawed, not or scarcely auriculate, fugacious; androecium 5-10-merous, 4.2-6 mm long, all or only five anthers functional, or some of the alternate ones functional but much smaller, the longer filaments free and blue-tinged for ± 0.8-1.2 mm; pod (little known) obliquely obovoid, ± 2.5 mm long, the valves thinly papery or submembranous, gland-sprinkled distally, finally separating along the sutures; seed ±1.5 mm long.At early anthesis the relatively uncommon D. urceolata closely resembles its widespread relative D. leporina, differing principally at that stage in its glabrous calyx-tube and in the presence of only one (not two) pair of fugitive little inner petals, which are cast off as the androecium emerges from the bud. Later on the calyx swells up into an ovoid or even subglobose bladder, striped lengthwise by the slender livid ribs and charged on each broad, glossily hyaline interval with a line of large orange blister-glands. In fruit D. urceolata is thus easily distinguished both from D. leporina and from the also related D. exserta, as discussed in greater detail under the foregoing species.

No less than five specific names have been based on forms of D. urceolata: in addition to the oldest, D. inflata Jones, Parosela barberi and lucida Rydb., and Petalostemon tripe talus Wilson. The differential characters, real or supposed, are found in habit of branching, number of leaflets, presence or absence of the single pair of epistemonous petals, and number of stamens, functional or partly degraded, to the androecium. In the pine forests and adjacent grasslands of Sierra Madre Occidental northward from Durango into central Arizona all known races of Dalea urceolata are characterized by a 7-10-merous androecium the number of antheriferous members sometimes varying from 7 to 10 from flower to flower of a single plant. In the Neovolcanic Belt from southern Jalisco to Morelos the stamens are 5-7, always five fully fertile members with an indeterminate number of intervening rudiments, some of which may bear small anthers. From Chihuahua northward in the Sierra Madre, as also in south-central Mexico, there are always, so far as observed, two epistemonous petals, though these are so fugitive that their presence is best determined by dissection of an unopened flower. Locally in Durango the corolla is reduced to banner alone. In northern Sierra Madre leaflets of main cauline leaves tend to be relatively few, most commonly in the range of 5-11 pairs, but up to 14 pairs are seen on specimens (G. J. Harrison 4895) from Gila County, Arizona. The same latitude of variation is known from the Neovolcanic Belt in Mexico, where maximum numbers of 9-13 pairs are on record. In both areas the plants differ among themselves in mode of branching, some giving rise from axils closely following the cotyledons to one or several incurved-ascending major branches, often overtopping the primary central axis, others retaining a simple erect stem with the first axillary branch issuing from an axil near or beyond the middle. Independently of these variable features the calyx-teeth may be relatively short or long, when short appearing relatively broad, by reduction of the terminal cusp. Within the species, sensu lato, there seems to be no decisive morphological discontinuity, only three fairly well marked geographic expressions of a variable theme, treated below as three varieties.

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.

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