NATIVE WOODY PLANTS OF THE UNITED STATES 225 



Rhamnus rubra Greene. Redstem buckthorn. 



Range : 4. 



Site : Well-drained, sun. 



Fruit: Drupe, available August-September. 



A small shrub ; flowers in June ; susceptibility to crown rust of oats not 

 known. 



Rhamnus smithii Greene. Smith buckthorn. 



R. fasciculuta Greene. 

 Range: 11, 13, 14. 

 Site : Well-drained, moist, sun. 

 Fruit: Drupe. 



A small to large, dioecious, densely leafy shrub ; susceptible to the crown rust 

 of oats. 



Rhamnus texensis, see Colubrina texensis. 

 Rhamnus tomentella, see Rhamnus californica. 

 Rhamnus ursina, see Rhamnus californica. 



Rhapidophyllum hystrix (Fraser) Wendl. and Drude. Needle palm. 



Chamaerops hystrix Fraser, Corypha hystrix (Fraser) Desf., Sabal hystrix 

 Desf. 



Range: 29, 30. 

 Site : Dry, well-drained, sun. 

 Fruit : Drupe. 

 A small to large evergreen shrub; rootstocks creeping and rooting. 



Rhododendron spp. 



This genus has often been divided into several separate genera or genus 

 sections. The most notable for the United States are rhododendron and azalea. 

 It is generally agreed among botanists that these two cannot be maintained as 

 separate genera although they may well appear to be separable as far as the 

 species in this country are concerned. They are here treated as one. The 

 species popularly known as azaleas are largely deciduous, at least in North 

 America. Those known as rhododendrons are mostly evergreen. The azaleas 

 are generally to be found growing in the sun ; the rhododendrons make their 

 best growth in the shade. Nevertheless, there are no constant botanical char- 

 acters to separate them. 



Rhododendron alabamense Rehd. Alabama azalea. 



Azalea alabamense (Rehd.) Small. 

 Range: 28, 29, 30. 

 Site : Dry, well-drained, sun. 

 Fruit: Capsule. 

 A small shrub ; flowers April-May. 



Rhododendron albiflorum Hook. White-flowered azalea. 



Asaleastrum albiflorum (Hook.) Rydb., Azalea albi flora Kuntze., Cladotham- 

 nus campanulatus Greene. 

 Range: 4, 12. 

 Site : Well-drained, shade. 

 Fruit: Capsule. 



A small to large shrub ; flowers June-July. While under normal range con- 

 ditions it is not palatable to livestock, it is nevertheless poisonous. 



Rhododendron arborescens (Pursh) Torr. Smooth azalea. 



Azalea arborescens Pursh. 

 Range: 27. 



Site : Well-drained, moist, sun, shade. 

 Fruit: Capsule. 

 A small to large shrub or rarely a small tree ; flowers June-July. 



Rhododendron atlanticum (Ashe) Rehd. 

 Azalea atlantica Ashe. 

 Range: 28, 29, 30. 



Site: Dry, well-drained, sun, half shade. 

 Fruit: Capsule. 



A small shrub ; flowers April-May ; mat forming ; aggressive ; spreads by 

 means of stolons ; many often invade fields. 



