Dalea coerulea

Title

Dalea coerulea

Authors

Rupert C. Barneby

Scientific Name

Dalea coerulea (L.f.) Schinz & Thell.

Description

77.  Dalea coerulea (Linnaeus fil.) Schinz & Thellung

(Plate LXXIX)

Irregularly branching shrubs up to 1.5-3, rarely 5 m tall, sometimes precociously flowering as suffrutescent herbs, with castaneous or livid, low-tuberculate and striate branches, pilosulous throughout or nearly so with fine soft ascending and subappressed, finally rufescent or golden hairs up to 0.3-0.6 mm long, the young foliage silky-canescent becoming green or greenish, the leaflets glabrous above, pubescent and punctate beneath, the vesture often becoming longer, looser and denser toward the inflorescence, the peduncles sometimes loosely hirsute distally; leaf-spurs 0.8-2 mm long; stipules narrowly subulate to linear-caudate, reddish or livid becoming fuscous and fragile, 1.3-4 mm long; intrapetiolular glands spiculiform, up to 0.2-1 mm long; post-petiolular glands rather small, rounded or conic; leaves shortly petioled, the main cauline ones (2.5) 3-11 cm long, with narrowly thick-margined rachis and 5-9 pairs of oblong, oblong-obovate, elliptic-oblanceolate, rarely obovate-cuneate, obtuse or subacute, gland-mucronate, dorsally carinate, flat or loosely folded leaflets 6-16 (20) mm long, the leaves of some axillary spurs shorter, with few (3-6) pairs of smaller leaflets; peduncles 1-2 leaf-opposed and subsequently several terminal to leafy branchlets, (0) 1-9 (11) cm long; spikes many-flowered, dense (or looser near base) but not conelike, narrowly ovoid and blunt-tipped becoming cylindroid, without petals or androecia 11-18 mm diam, the calyces subcontiguous and (pressed) several- ranked, the densely silky-pilosulous axis becoming 3-14 cm long; bracts persistent at least till past anthesis, the body (2.5) 3-4.3 mm long, broadly ovate or ovate- oblong, clasping the flower-buds, in profile (1.2) 1.4-2.1 (2.3) mm wide, papery- castaneous within the submembranous margins, dorsally keeled and either subglabrous or thinly pilosulous to pilose, abruptly contracted or tapering into a divaricate tail much shorter than or up to ± as long as body, mostly 0.5-3.5, rarely 4.5 mm long; calyx (5.2) 5.4-8.4 mm long, pilose on tube or teeth or both with fine ascending, finally divaricate hairs up to (0.6) 0.8-1.6 (2) mm long, the tube 2.4-3.2 (3.7) mm long, the prominent ribs castaneous or livid, the membranous intervals charged with at least 1 or up to 5 (6) glands variable in size and color, the orifice subsymmetrical, the teeth triangular at base, contracted into a stout mucro or flexuously spreading, gland-spurred arista, nearly always somewhat unequal, the dorsal one longest, varying from as long up to ± twice as long as tube; petals bicolored, the banner opening white except for blue-tipped lobes, early rubescent, with a 1-lobed greenish spot and a cluster of glands near the eye, at least dorsally and sometimes ventrally pilosulous near base of blade, the epistemonous petals commonly ultramarine or cobalt blue, rarely violet- or magenta-purple, exceptionally white (albino), perched at 1.2-2.8 (3.1) mm above hypanthium, the blades gland-tipped; banner 5.3-8.4 (9.6) mm long, the claw 2.4-4.2 (4.8) mm, the broadly obovate-cordate, emarginate blade (3.3) 3.5-5 (6) mm long, 3.8-5.2 (5.8) mm wide; wings (5) 5.6-7.9 (9.8) mm long, the claw (1.7) 2-2.9 (3.4) mm, the oblong, elliptic, or elliptic-obovate blades 4.3-5.8 (6.4) mm long, 1.8-3.2 (3.7) mm wide; keel 6.8-11.6 (12) mm long, the claws 2.3-4.7 mm, the broadly ovate-elliptic blades (4.8) 5-8.2 mm long, 2.4-4.7 mm wide; androecium 10-merous, 7-14 mm long, the filaments free for up to 2.2-4.2 mm, the connective gland-tipped, the anthers 0.5-0.9 mm long; pod varying from obliquely obovate to obtusely deltate in profile, 2.6-3.2 mm long, the style-base latero-terminal, the prow slenderly keeled, the valves hyaline in lower half, thence thinly papery, pilosulous, sparsely gland-sprinkled; seed ± 2 mm long.As described and defined herein, D. coerulea is a variable and polymorphic species dispersed along the Andes, mostly east of the Divide, from latitude 8° 20' N in Colombia’s Cordillera Oriental south to 13° 10' S in the gorge of the Urubamba in Cuzco, Peru. Between Bogota and the headwaters of Rio Maranon in Peru it is the commonest and most often collected member of the genus, readily recognized by its tall shrubby habit, ample leaflets glabrous above, and thick, densely flowered spikes of handsome blue and white flowers. With the exception of sympatric but uncommon D. ayavacensis, set off (perhaps artificially) by the pairs of linear glands occupying the length of each intercostal membrane of the calyx, it is the only dalea of its type characterized by long calyx-teeth, the dorsal one varying from as long up to twice as long as the tube. Over a great central segment of its range D. coerulea is sympatric with the habitally similar, also blue-flowered D. cylindrica var. nova, and in Cajamarca apparently intergrades with it. The apically glabrate, corneous-margined calyx-teeth of var. nova, ordinarily all decisively shorter than the tube, are its best differential characters.

The numerous races of D. coerulea differ one from the next in length of spike, in length of bracts, in flower-size (and consequently in thickness of the spike), in gland-patterns on the intercostal calyx-membranes, and particularly in the length and dispersal of hairs over the calyx-tube and teeth. Most commonly, in Colombia almost always, the calyx-tube is glabrous and lustrous, contrasting with plumosely ciliate teeth, and a calyx of this type, varying however in proportion of its parts, prevails through the range of the species. In Ecuador and sporadically southward the tube is pilose in varying degrees, sometimes only around the orifice, but sometimes only at base, or only on the dorsal side, or from the base upward its whole length. Every stage from hairless to densely pilose is now known to occur, and the variation seems unrelated to any other feature. Collections such as Prescott 134 (NY), which include branches, seemingly identical otherwise, bearing two different pubescence-patterns on the calyces, demonstrate the insignificance of this character. It is also clear that variation within a rather wide range must be accepted for the calyx-teeth of D. coerulea, and this without known geographical or morphological correlation. On the other hand the majority of collections from south of Chachapoyas in Peru have larger flowers, thicker spikes, and ampler petals than prevail north of that point, and it is therefore possible to maintain a weakly characterized var. longispicata.

In Colombia the calyx-glands are only one or two in each interval, usually crowded below the middle or at very base of each membrane, and this pattern is repeated southward at least to the Equator, becoming however rarer toward the south. Sporadically in Colombia and then ever more commonly, each interval is charged with additional small glands set in a single (sometimes irregular) row extending into the base of the calyx-teeth. Southward the individual glands tend to become larger, but are not known to coalesce into the linear glands that characterize D. ayavacensis.