Dalea similis
Rupert C. Barneby
68. Dalea similis Hemsley
(Plate LXX)
Doubtless perennial (base of stem and root not seen), resembling D. crassifolia and D. pectinata in habit, with erect, virgate, leafy stems over 1 m tall branching distally into a several-headed, cymose panicle of spikes, densely and softly villous- tomentulose throughout with fine, sinuous, entangled together with some few straighter, spreading hairs up to 0.4-0.6 mm long, the stout, ribbed stems gray like the foliage, minutely glandular beneath the vesture, the leaflets equally pubescent both sides, inconspicuously punctate beneath; leaf-spurs 0.5-1.2 mm long; stipules narrowly linear-subulate, livid, fragile, 0.8-2.5 mm long; intrapetiolular glands 0 or minute; post-petiolular glands small, impressed, concealed by vesture; main cauline leaves 3-6 cm long, sessile, with stout, narrowly thick-margined rachis constricted at insertion of the leaflets, and 12-23 pairs of sessile, ovate to oblong-elliptic, subacute, shallowly boat-shaped leaflets (1) 1.5-5.5 mm long, the lowest pair substantially longer than the second pair, the rest very gradually diminishing upward along the rachis, the terminal one absent, represented by a subulate continuation of the rachis shorter than the ultimate pair, the leaves toward and within the inflorescence much shorter and simpler, with 6-12 pairs of smaller, otherwise similar leaflets; peduncles 1-2 cm long, but often appearing longer due to suppression of leaves at some upper nodes; spikes dense but hardly conelike, oblong-ovoid becoming shortly cylindroid, without petals ± 12 mm diam, the villous axis becoming ± 1.5-5.5 cm long; bracts deciduous, narrowly lance-acuminate, 4-6 mm long, the ovate, saccate-cymbiform body contracted gradually into a subulate, beaklike tail of ± equal length, the whole tomentulose dorsally, livid-castaneous and glabrous within; calyx 4-5.7 mm long, densely pilose externally with ascending, straight, spiral hairs up to 0.8-1.2 mm long, the tube measured to a dorsal sinus 2-2.5 mm long, the ventral sinus deeply recessed behind the banner, the orifice oblique, the ribs slender, not prominent, the membranous flat intervals charged with 4-9 small, scattered (in narrower panels ± 1-seriate) glands, the triangular-acuminate, gland-spurred teeth somewhat unequal, the dorsal one longest, 2-3.2 mm long (0.5 mm shorter to 0.8 mm longer than tube), the ventral pair a little shorter but hardly wider; petals faintly bicolored, the banner opening white, in age purplish, its eye charged with a few scattered glands, the epistemonous petals pale lilac, perched 0.8-1.3 mm above hypanthium rim, glandless; banner 5.5-6 mm long, the claw 2.8-3 mm, the ovate-deltate, distally hooded blade open at base but with comers folded inward, 2.8-3.2 mm long, 3 mm wide; wings 5.2-6 mm long, the claw 2-2.5 mm, the oblong-obovate blade 3.3-3.7 mm long, 1.5-1.8 mm wide; keel 6.8-7.3 mm long, the claws 2.8-3.6 mm, the elliptic-obovate blades 3.6-4.3 mm long, 2.2-2.5 mm wide; androecium 6.5-7.5 mm long, the filaments free for up to 1.8-2.8 mm, the connective gland-tipped, the anthers yellow, 0.55-0.6 mm long; pod when young like that of D. polystachya, not seen ripe. — Collections: 4 (o).
Sunny hillsides in pine-oak forest, ± 1500-1950 m (5000-6500 ft), rare and local, known only from the w. slope of Sierra Madre Occidental in Sinaloa (perhaps immediately adjoining Durango). — Flowering January to March, possibly later. —Material: Durango (?): Cerro del Pinal, typus. Sinaloa . Concordia: Durango-Mazatlan highway at El Batel, Gentry 11,563 (MEXU, MICH, RENNER); 33 mi e. of Concordia, Breedlove 1665-A (MICH); 34 mi. e. of Villa Union, Ockendon 1406 (TEX).
Dalea similis (similar, apparently to D. crassifolia) Hemsley, Diag. Pl. Nov. 7. 1878.—"Cerro del Pinal, Durango, Seemann, 1533..." — Holotypus, collected December 1848, K (herb. Hook.)! isotypus, labelled "West Mexico, Hooker, 1849", K (herb. Benth.)!—Parosela similis (Hemsl.) Rose, Contrib. U. S. Nat. Herb. 12: 273. 1909.
This rare and strikingly individual dalea may be recognized by a syndrome of dense villous vesture and paripinnate leaves composed of many (mostly 12-23 pairs) of small, essentially sessile leaflets diminishing upward along a stout rachis. The terminal leaflet is wanting, but is represented by a small, unjointed projection of the rachis shorter than the last pair of leaflets. The lowest pair of leaflets, situated directly next to the pulvinus, is substantially larger than the second pair, a feature unusual in Dalea but found also in the related and sympatric D. pulchella, a species otherwise very different in its glabrous, warty stems, small, round, glabrous leaflets, and bright purple flowers. In general organization and fine detail of the inflorescence, especially in the dorsally recessed calyx and pale lavender petals, D. similis resembles the also sympatric D. crassifolia, another rarely collected species discovered by Seemann on his round trip between Mazatlan and Ciudad Durango in the winter months of 1848-9. This is easily distinguished, however, by its glabrous stems and glabrous, regularly pinnate foliage. The similarly gray-villosulous D. abietifolia, a rare species known at present only from scattered stations in Jalisco and Michoacan, suggests D. similis in habit, but is usually a lower plant, up to about 6 dm (not over 1 m) tall; its leaflets are proportionately longer and narrower, the terminal one well developed, its calyx is little or not at all recessed behind the banner, and the petals (wings and keel) are vivid purple.
Breedlove describes the plant as annual, but an obligate monocarpic habit seems unlikely in the context of ser. Pectinatae. Possibly it is monopodial. Specimens collected by Ockendon at the end of January are in young flower from drought-defoliated stems, but these are so tall that no herbarium specimen is likely to show the full stature or the root.
I have not identified Seemann’s Cerro del Pinal, though it was doubtless on the west slope of Sierra Madre east of Mazatlan near the old trail across to Durango City.
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:
