Luteyn, James L., et al. 1995. Ericaceae, Part II. The Superior-Ovaried Genera (Monotropoideae, Pyroloideae, Rhododendroideae, and Vaccinioideae P.P.). Fl. Neotrop. Monogr. 66: 560. (Published by NYBG Press)
Ericaceae
Species Description - Erect to spreading, low, rounded, often gnarled shrubs, 0.2-2 m tall; young twigs and petioles puberulent to hirtellous to subcanescent, trichomes usually eglandular. Leaves conduplicately folded at maturity or plane, 3.3-5.5 × 0.6-1.9 cm, apex obtuse to acute but usually mucronate, lower surface subglabrous to puberulent. Inflorescences 2.5-6.2 cm long, rachis, pedicels, bracts, bracteoles, and calyx puberulent, also usually with stalked, swollen-headed glandular trichomes. Flowers with ovary glabrous or sparsely pilose. Fruit 4-6 mm in diam.
The subspecies can be recognized by the combination of its small size (= 2m tall), usually conduplicately folded, oblong to oblong-ovate leaves, puberulent, hirtellous to subcanescent stems, puberulent inflorescences (also usually with glandular trichomes), and distributional range. While the taxon is morphologically distinct, I agree with Henrickson (1981) that subsp. coahuilensis fits within the range of variation of the diverse C. polifolia and that subspecies rank is the most justifiable.
Distribution and ecology: Subspecies coahuilensis is known from seven mountain ranges in the central Chihuahuan Desert of southern and central Coahuila, Mexico. The taxon occurs in areas of "matorral xerofilo" (Rzedowski, 1978) or open chaparral (Henrickson, 1981) with Acacia berlandieri, Agave sp., Cercocarpus sp., Dasylirion sp., Garrya sp., Leucophyllum sp., Nolina sp., Opuntia sp., Ptelea trifoliata, Quercus sp. and Yucca carnerosana. It can also be found at higher elevations in forests of Abies coahuilensis, Pinus strobiformis, P. arizonica, Pseudotsuga menziesii, Quercus greggii and Cupressus arizonica (Henrickson, 1981). The subspecies is apparently restricted to limestone or limestone and gypsum substrates at approximately 1500-2600 m elevation. Flowering Apr-Aug; fruiting Jul-Nov.
Mexico North America| Coahuila Mexico North America|
madroño, madrona