ERICACE. 
lit SILVA OF NORTH AMERICA. 
Nearly two hundred species of Rhododendron are already known ;' they abound in western Thibet ” 
and on the Himalayas* and their western prolongation in southwestern China ;‘ through the Malay 
Peninsula and Archipelago, where several species inhabit the high mountain forests, they range to 
New Guinea,’ and through central and northern China and Corea‘ to Japan,® where a dozen species are 
found; of these, Rhododendron Camtschaticum® reaches Alaska” by the Kurile Islands.” Fifteen 
or sixteen species, representing seven of the nine sections into which the genus has been divided, 
inhabit North America,” where they are chiefly confined to northern regions and high mountain ranges, 
a larger number occurring in the eastern than in the western part of the continent. Only Lthododen- 
dron Lapponicum® crosses the continent, ranging from the shores of Norton Sound to Labrador and 
the alpine summits of the White Mountains in New England, and by way of Greenland reaching Europe 
and northern Asia. In the extreme western part of Europe two other species “ are found, while a third” 
inhabits the high mountain ranges of the central regions of the continent. Five species are found in 
the Orient; ' the genus reappears in Afghanistan with two endemic species,” and rapidly increases 
in the number of species from west to east on the Himalayas. Rhododendrons were common in the 
Arctic regions of both hemispheres during the tertiary period, and traces of several species are found 
from separate cone-like buds of many caducous bracts on shoots of 
the previous year ; corolla 5 to 10-lobed, glabrous or pilose in the 
throat ; stamens 10 to 20. Trees or shrubs with persistent leaves. 
Eastern and Pacific North America, Europe, Asia Minor, Hima- 
layas, China, and Japan. 
AZALEA. Flowers in many-flowered terminal clusters from sepa- 
rate cone-like terminal buds of many caducous bracts on shoots of 
the previous year ; corolla funnel-form or campanulate-rotate, the 
limb 4-lobed or parted, rarely bilobed ; stamens 5 to 10, exserted. 
Shrubs with membranaceous or rarely coriaceous deciduous leaves. 
Eastern and western North America, Asia Minor, China, and 
Japan. 
Tsusra. Flowers terminal from leafy buds of few caducous 
scales on shoots of the previous year ; corolla campanulate ; sta- 
mens 5 to 10; ovary 5-celled. Glandular shrubs with deciduous or 
persistent leaves. China and Japan. 
Keys1a. Flowers fascicled from axillary buds ; corolla tubular- 
cylindric, the lobes incurved ; stamens 10 ; ovary 5-celled. A shrub 
with persistent leaves. Himalayas. 
RuoporasTruM. Flowers solitary from axillary buds ; corolla 
campanulate ; stamens 10. Shrubs with deciduous lepidote slightly 
coriaceous leaves. 
AZALEASTRUM. Flowers axillary from the same bud as the leafy 
Northern Asia, Himalayas, and eastern Thibet. 
shoot or from separate 1 to 3-flowered buds ; corolla rotate or sub- 
campanulate ; stamens 5 to 10. Shrubs with coriaceous or mem- 
branaceous deciduous leaves. Northwestern America, eastern 
Thibet, China, and Japan. 
THERORHODION. Flowers in 1 or 2-flowered clusters from buds 
terminal on the leafy shoots of the year, their bracts persistent on 
the base of the branch during the season ; corolla rotate, 5-lobed, 
divided on the anterior side to the base ; stamens 10. Low shrubs 
with deciduous leaves. Northwestern America and northeastern 
Asia. 
To these sections Franchet (Bull. Soc. Bot. France, xxxiii. 229) 
adds a ninth : — 
CHonrAsTRUM. Flowers in 1 or 2-flowered fascicles from axil- 
lary buds; corolla infundibular; stamens 13 to 14, exserted. Leaves 
Southwestern China and eastern Thibet. 
1 Although botanical travelers have as yet hardly penetrated 
persistent. 
that great central Asiatic region where the Himalayan system is 
prolonged to the west and northwest in high mountain ranges, 
they have recently made known a large number of previously unde- 
scribed Rhododendrons, transferring the headquarters of the genus, 
as represented by the greatest number of species, from Sikkim to 
Yun-nan ; and a further examination of the forests which cover 
the mountains of western and southwestern China, eastern Thibet, 
and northern Burmah may be expected to yield large additions to 
the number of species. 
2 Franchet, Pl. David. ii. 83. 
8 Hooker f. Rhododendrons of the Sikkim-Himalaya; Fl. Brit. 
Ind. iii. 462. 
4 Franchet, Bull. Soc. Bot. France, xxxiii. 223. 
5 Miquel, Fl. Ind. Bat. ii. 1057. 
6 Beccari, Malesia, i. 199.— Warburg, Engler Bot. Jahrb. xvi. 
24. 
7 Maximowicz, Mém. Acad. Sci. St. Pétersbourg, sér. 7, xvi. 13 
(Rhododendree Asie Orientalis).— Forbes & Hemsley, Jour. Linn. 
Soc. xxvi. 19. 
8 Franchet & Savatier, Enum. Pl. Jap. i. 287. 
® Pallas, Fl. Ross. i. 48, t. 23 (1784). — De Candolle, Prodr. vii. 
726. — Hooker, Fl. Bor.-Am. ii. 43. — Ledebour, Fi. Ross. ii. 922. — 
Regel & Tilling, Tent. Fl. Ajan. 110. — F. Schmidt, Afém. Acad. 
Sci. St. Pétershourg, sér. 7, xii. 157 (Fl. Sachal.). — Maximowicz, 
L. c. 47. 
Rhodothamnus Kamtschaticus, Lindley, Paxton Brit. Fl. Gard. i. 
113, t. 22 (1850). 
10 Gray, Syn. Fl. N. Am. ii. 40. 
11 Miyabe, Mem. Bost. Soc. Nat. Hist. iv.247 (Fl. Kurile Islands). 
12 Gray, l. c. 39. 
18 Wahlenberg, Fl. Lapp. 104 (1812). — Bot. Mag. lviii. t. 3106. — 
Hooker, J. c. — De Candolle, J. c. 724. — Gray, I. c. 42. — Watson 
& Coulter, Gray’s Man. ed. 6, 321. 
Azalea Lapponica, Linneus, Spec. 151 (1753). — Fl. Dan. vi. 
t. 966. — Pallas, 1. c. ii. 52, t. 70, f. 1. 
14 Nyman, Conspect. Fl. Europ. 491. — Hooker f. Bot. Mag. exvi. 
t. 7149. 
18 Rhododendron ferrugineum, Linneus, 1. c. 392 (1753). — Jac- 
quin, Fl. Austr. iii. 31, t. 255. — Hayne, Arzn. x. 25, t. 25. — 
Guimpel, Willdenow & Hayne, Abbdild. Deutsche Holz. i. 69, t. 
52. — Nees von Esenbeck, Pl. Med. t. 217. — De Candolle, /. c.— 
Nyman, J. c. 492. 
16 Boissier, Fl. Orient. iii. 971.— Trautvetter, Act. Hort. Petrop. 
ix. 513. — Gartenflora, 1886, 377, t. 1226. 
17 Aitchison & Hemsley, Jour. Linn. Soc. xviii. 75. 
