98a.  Dalea cyanea Greene var. cyanea

(Plate XCI)

Very variable in pubescence, the foliage green and glabrous except for a few scattered hairs on the leaf-rachis, or softly and finely pilose except for glabrate upper face of the leaflets; 2n = 7 II (Mosquin); otherwise as given in the key. — Collections: 10 (ii).

Open sunny slopes and canyon benches, in oak-pine forest, 1950-2500 m (± 6800- 8300 ft), locally common on the east slope of the Sierra Madre due w. and s.-w. of Ciudad Durango, Durango. — Flowering July to October. — Material: Durango. Empalme Purisima, Pennell 18,253 (NY). El Salto road, at points 26-51 mi w. of Durango, Waterfall 13,729 (OKLA), 16,180 (NY, OKLA, UC), Maysilles 8083 (US), Correll & Johnston 20,121 (RENNER), Ripley & Barneby 13,488 (CAS, NY, US), 14,002 (CAS, MEXU, MICH, NY, US), Mosquin et al. 6878 (NY).

Dalea cyanea (blue) Greene, Pittonia 1: 153. 1888.— "...by Mr. A. Forrer, in the autumn of 1881, on the higher Sierra Madre back of the city of Durango, in Mexico... about 8100 feet." —Holotypus, ND (?), not seen; isotypi, F, UC, US!— Parosela cyanea (Greene) Rose, Contrib. U. S. Nat. Herb. 10: 105. 1906.

Parosela pilosissima (densely hairy) Rydb., N. Amer. Fl. 24: 91. 1920.— "Type collected at the city of Durango and vicinity, 1896, Palmer 808..." — Holotypus, GH! isotypi, F, UC, US!—Dalea pilosissima (Rydb.) Bullock, Kew Bull. 1939: 197. 1939.

The mature plant of D. cyanea forms a cartwheel, up to 7 dm in diameter, of radiating reddish stems that branch paniculately near or above the middle, each branchlet bearing aloft on an incurved peduncle a tight, knoblike head of particolored flowers. In the newly opened flower the banner is white, or white tipped with blue, but the white area soon turns reddish; the inner petals are an intense, sparkling blue. Commonly the stems are thinly pilosulous and the main cauline leaves green and glabrous, but the caudex of such plants gives rise, late in the year, to leafy spurs densely pilosulous throughout with fine, shining hairs. The typus of P. pilosissima is an example, comparatively rare in the species as now known, in which the stems and primary foliage are pilose like the autumnal spurs. Rydberg described P. pilosissima as a "low, intricately branched shrub", but there is nothing in the specimens to suggest such a habit of growth. The oldest plants of D. cyanea develop a somewhat suffrutescent caudex, but never become truly shrubby.

The range of D. cyanea as known from precise data lies athwart the Durango-El Salto highway across the Sierra Madre and has a circumference, measured east to west, of about thirty km. Its northern and southern limits along the Sierra are still to be ascertained. Gentry (1942, p. 137) tentatively identified as D. cyanea specimens collected in Chihuahua, at San Jose de Pinal and Memelichi, but these have turned out to represent a blue-flowered state of D. lumholtzii.