


ADJACENT TO HORTICULTURAL HALL. 53 

endrum. Sorrel-Tree, Sour-Woop. Tree often 40 feet high, 
with large (3 to 5 inches long) sour leaves on petioles an inch long; calyx-lobes 
nearly distinct; corolla somewhat hairy, cylindrical-ovate, contracted above; 
anthers opening by slit-like pores; white flowers in one-sided racemes on the 
ends of the year’s branches. Our species,—Oxydendrum arboreum, De 
Candolle,—ranges from Pennsylvania and Ohio southward along the mountains. 
Rhododendron (including Azalea and Rhodora). Calyx free from the 
ovary; pod-valves at maturity separating from the central seed-bearing part ; 
ae deciduous, regular, or irregular, ‘‘ but not contracted at the orifice ;” 
stamens long and slender, usually twice as many as the lobes of the corolla, 
bent downward ; anthers opening by a round terminal pore and destitute of any 
horn-like appendage. 
We include here simply recognized sfectes, and not the hundred or more 
beautiful varieties and hybrids which have been produced by cultivation and 
the names of which appear on the Park invoices. 
Azalea section of Rhododendron ; has the corolla usually long, funnel- 
form, and sticky outside; 5 stamens. 
* Rhododendron arborescens, Zorrey. Shrub 3 to 1o feet high; flowers 
fragrant, rose-colored, 2 inches or more long, appearing after the leaves, the 
latter slightly hairy along the margin, greener on the upper than on the lower 
surface; calyx-lobes narrowly oblong, somewhat large and conspicuous. 
Pennsylvania southward along the mountains. 
Rhododendron calendulaceum, 7Zorrey. FLAME-COLORED AZALEA. 
Shrub 3 to Io feet high; the bright, large, orange-colored or flaming-red 
flowers appearing with the leaves, not fragrant; calyx very small and incon- 
spicuous. It ranges from Pennsylvania through the Southern mountains. 
Rhododendron flavum, Dow. PontTic AZALEA. (Azalea Pontica, Lin- 
mzus.) Shrub 4 to 6 feet high, from the Levant; varies greatly in its flowers, 
and hybridizes so freely that it has produced a great number of garden forms. 
Honey made from this species in its native country is said to be poisonous. 
Rhododendron nudiflorum, Zorrey. PINXTER FLOWER. Shrub 4 to 6 
feet high, common on our hill-sides; flowers appearing with or before the leaves, 
from a light rose-color to bright purple. The tube is but little longer than the 
spreading part of the flower. ‘It varies greatly in the wild condition, pro- 
ducing in the South yellow flowers. Hybrid forms are common in cultivation. 
* Rhododendron Rhodora, Don. (Rhodora Canadensis, Linnaeus.) A low 
shrub ranging from Pennsylvania northward in the cold bogs; flowers irregu- 
lar, purple or rose-color, hardly an inch long (tube very short), appearing 
before the leaves, which are I to 2 inches long. 
Rhododendron viscosum, 7Zorrey. CLAMMY AZALEA, WHITE SWAMP 
HONEYSUCKLE. Shrub 4 to 10 feet high; flowers appearing after the leaves, 
white or slightly rose-colored; branchlets bristly hairy. 
Section of Rhododendron proper has the corolla open bell-shaped, stamens 
10; leaves thick. - 
Rhododendron Catawbiense, Michaux. Shrub from 3 to 20 feet high ; 
younger parts not scaly-scurfy; flower-stalks glandular hairy; leaves 3 to § 
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