Dalea compacta

  • Title

    Dalea compacta

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Dalea compacta Spreng.

  • Description

    47.  Dalea compacta Sprengel

    (Plate LVIII)

    Perennial herbs from a thick tough root and when adult a shortly forking caudex, 3-6 (7) dm tall, varying from almost glabrous (but at least stipules and often leaf- rachis retaining vestigial vesture) to thinly pilosulous nearly throughout with fine weak spreading-ascending hairs up to 0.3-0.6 (0.7) mm long, the stem either simple and monocephalous, but bearing leaf-spurs in most primary leaf-axils, or few-branched at or beyond middle, either erect, ascending, or diffuse, prominently ribbed, remotely punctate or microtuberculate, the foliage bluish-green or subglaucescent, the leaflets scarcely bicolored, punctate beneath; leaf-spurs almost 0 up to 1 mm long; stipules narrowly subulate to linear-aristiform, early dry and fragile, 1.5-5.5 mm long; intra- petiolular glands minute; post-petiolular glands small, not or scarcely protuberant; leaves petioled, the primary cauline ones (2) 2.5-5.5 cm long, with narrowly thick- margined, usually punctate rachis and (1) 2-3 (4) pairs of linear to linear-elliptic, mostly acute and mucronulate, flat but marginally involute or strongly inrolled leaflets up to (1) 1.2-2.5 cm long, the leaflets of axillary spurs similar but mostly 3 and shorter; peduncles 0-15 cm long; spikes very dense and conelike, ovoid becoming oblong or subglobose, each side composed of ascending spirals of 5-8 calyces, the whole without bracts, petals or androecia 10.5-14 (15) mm diam, the pilosulous axis (0.5) 1-3 cm long; bracts persistent, the lowest firm, thinly pilosulous or glabrate, ovate to ovate-acuminate or -caudate, the upper ones obovate to oblanceolate, contracted into a glabrous, livid tip 0.7-4 mm long, papery at very base, usually velvety- pilosulous dorsally at middle; calyx (4.4) 5-6.2 mm long, densely pilosulous about the orifice, along margins of teeth, and in lines along the obtuse angles below each sinus, with dense, plushlike indument of subappressed and ascending hairs up to 0.1-0.25 mm long, the tube 3-3.8 mm long, not recessed behind banner, at base membranous and brownish, thence (dry) appearing either whitish or glaucous-green (but brownish within or when moistened), the ribs immersed, the intervals firm, eglandular or minutely livid-punctate, the teeth of subequal length but dissimilar in form, the 3 dorsal ones broadly subulate, the ventral pair deltate-ovate, the longest (1.2) 1.4-2.4 mm long; petals concolorous, vivid rose-lilac or rose-purple, glandless; banner 5.4-9 mm long, the claw 3.4-5.8 mm, the ovate-oblong or -deltate, basally cordate or truncate, apically obtuse, strongly hooded blade 2.2-3.5 mm long, 2.4-3.6 mm wide; epistemonous petals all alike, 3.5-5.4 mm long, the claw 0.6-1.8 mm, the oblong or oblong-oblanceolate blades 2.8-4 mm long, 1.1-1.8 mm wide, at base either 2- auriculate or cuneate, at apex hooded, obtuse or emarginate; androecium 8-10.5 (11-2) mm long, the column 4.5-5.6 (6) mm, the purple free filaments up to (3.3) 3.5 (5.4) mm long, the connective gland-tipped, the anthers orange-yellow, 1.15-1.5 mm long; ovary glabrous or very thinly pilosulous at apex; pod (little known) obliquely obovoid, 3-3.5 mm long, the style-base excentrically terminal, the prow transversely dilated, corneous.

    A species closely related to D. purpurea, with which it hybridizes in Red River valley (Wemple, 1970, p. 74), but differing in the larger, obtuse-angled calyx glabrous and pallid- glaucescent distally except for lines of plushlike pubescence around margins of the teeth, orifice, and often along the angles of the tube. In general the flowers, and so the spikes, are larger, the androecia longer, and the petals more ample. The superficially very similar D. tenuis is readily distinguished by the retrorse pubescence of the calyx-tube. The species is variable in growth-habit, length of peduncle, and particularly in length of interfloral bracts, the last two becoming longer in the eastern third of the species-range. Hesitantly I follow tradition in recognizing within D. compacta two intergradient entities corresponding with Petalostemon decumbens and P. pulcherrimum as defined by Wemple; they are weakly differentiated but seem to follow a geographic pattern of some significance. For interpretation of the name D. compacta, long ago erroneously transferred to the species herein called D. cylindriceps, see under var. compacta following.