张口杜鹃 zhang kou du juan

Rhododendron chasmanthum Diels, Notes Roy. Bot. Gard. Edinburgh 5: 212. 1912; R. augustinii var. chasmanthum (Diels) R. C. Fang; R. augustinii f. grandifolium Franchet; R. augustinii f. hardyi (Davidian) R. C. Fang; R. augustinii subsp. hardyi (Davidian) Cullen; R. augustinii f. rubrum (Davidian) R. C. Fang; R. augustinii subsp. rubrum (Davidian) Cullen; R. augustinii var. rubrum Davidian; R. augustinii f. subglabrum Franchet; R. bergii Davidian; R. chasmanthoides I. B. Balfour & Forrest; R. hardyi Davidian; R. hirsuticostatum Handel-Mazzetti.

Less hairy on all parts; young shoots glabrous. Petiole often glabrous; abaxial leaf surface scales (1–)2–5 × their own diameter apart, otherwise often glabrous; adaxial surface without filiform-acicular hairs; corolla white, pinkish purple or lavender to blue; style base often glabrous, rarely pubescent.

Evergreen broad-leaved forests, mixed forests on valley sides, Abies and other coniferous forests, thickets on rocky mountains; 1700–3400(–4200) m. Gansu, Sichuan, Yunnan.

In FRPS (57(1): 65. 1999) both Rhododendron augustinii f. hardyi and f. rubrum are mentioned. The first has leaves deciduous and corollas white with brownish spots. The second has petioles with loriform and filiform-acicular hairs and corollas pinkish purple. These two entities are clearly distinct in cultivation, but are considered to have a dubious status in the wild (see Cullen, Notes Roy. Bot. Gard. Edinburgh 39: 73–74. 1980).