AND GENERAL HORTICULTURE. 



367 



RET 



and make very pretty hedges, especially R. 

 obtusa aurea. They are worthy of being largely 

 planted. Introduced in 1864. This genus is 

 placed by some botanists under Chamoecyparis. 



Retuse. Terminating in a round end. 



Revolute. Rolled back; as certain tendrils, 

 and the sides and ends of some leaves. 



Rhamna'ceae. A natural order of trees or 

 shrubs, inhabiting warm and tropical regions. 

 The branches are often thorny or prickly, 

 with the flowers in axillary or terminal clus- 

 ters, cymes or panicles. The most useful 

 genera, from an economic point of view, are 

 RhamnuH, and Zizyphus, the species of which 

 yield medicinal juices. Rhamnus dururicus, 

 and R. tinctorius, yield the famous Green In- 

 digo, the Lo-Kao of China, quantities of which 

 have been imported into Lyons and used for 

 dyeing silks, the shades of green imparted by 

 it being exceedingly beautiful. The order 

 consists of about forty genera and over four 

 hundred species. Well-known examples are 

 Rhamnus, Ceanolhua, Cobletia, Phylica, and 

 Hovenia. 



Rha'mnus. Buckthorn. From rhnm, a Celtic 

 word signifying a tuft of branches. Nat. Ord. 

 Rhamnacece. 



An extensive genus of hardy deciduous and 

 green-house evergreen shrubs, the more use- 

 ful and common being R. catharticus, common 

 in Great Britain, where it is much grown as a 

 hedge plant. The fruit of this species was 

 formerly in great demand for its medicinal 

 properties. The Alder Buckthorn, R. Fran- 

 gula, affords a coloring matter, and the most 

 important commercial product of the genus is 

 the dyeing material used by calico printers, 

 and known as Yellow-berries, or Persian Ber- 

 ries, considerable quantities of which are an- 

 nually imported from Asiatic Turkey and 

 Persia. Although usually ascribed to -R. in- 

 fectoriu3, they are probably collected indis- 

 criminately from several species, the unripe 

 fruits alone being gathered. R. Caroliniana, 

 (Indian Cherry) forms small bushes, which in 

 summer are covered all over with small 

 greenish flowers, unripe and ripe small, but 

 very ornamental, red and black fruit in im- 

 mense profusion. R. crocea, is widely dis- 

 tributed on the Pacific coast, from the valley 

 of the Upper Sacramento to Arizona. It most 

 frequently occurs as a low, spreading bush, 

 five to ten feet high, though in some localities 

 it becomes quite arborescent, with a trunk 

 ten inches in diameter. R. insularia, of 

 Greene, is thought by Professor Sargent to 

 be a variety of this species, and which he 

 proposes to call R. crocea, var. inaularia. It 

 is one of the Mexican species, and is found in 

 the Santa Barbara and Cedar Islands, off the 

 Californian coast, and also on the mainland 

 (Santa Cruz Mountains). It bears black, bilo- 

 cular fruit, and is a much larger plant in every 

 way. More information than now exists, 

 based upon field observation upon the differ- 

 ent California species of Rhamnus, is very 

 desirable. Proper limitations of the different 

 species and varieties are still doubtful, and 

 really nothing is known of the life histories of 

 these plants. 



Rhaphido'phora. From raphidos, a needle, and 

 phero, to bear; alluding to the needle-like 



RHE 



hairs which abound in all parts of the plants. 

 Nat. Ord. Aroidece. 



A large genus of climbing stove-house 

 shrubs, with very large rooting branches, 

 natives of tropical Asia, the Malayan Archi- 

 pelago and the Pacific Islands. A few species 

 are cultivated in plant-stoves to cover walls 

 or dead stems of trees, but they are rather 

 coarse, except in large collections. 



Rhapidophy'llum. From rhapis, a needle, and 

 phyllon, a leaf ; in reference to its resemblance 

 to the genus Rhapis, both producing suckers 

 freely a character by no means common in 

 the Palm family. 



R. Hystrix (Blue Palmetto), a low-growing 

 species with a short erect or creeping trunk, 

 is a native of the Southern States, and is 

 known in cultivation as Chamcerops Hystrix. 



Rhaphio'lepis. Indian Hawthorn. "From rhapis, 

 a needle, and lepis, a scale ; alluding to the 

 subulate bracts. Erroneously spelled Raphio- 

 lepis. Nat. Ord. Rosacece. 



A genus of evergreen shrubs found in China 

 and Japan. They are nearly allied to Cratcegus, 

 from which they are distinguished by their 

 flowers being produced in panicles instead of 

 clusters. -R. Indica and its varieties are nearly 

 smooth evergreen shrubs, with short terminal 

 panicles of white or pink-tinted flowers of the 

 size of those of the Hawthorn. They have 

 been introduced into the green-house. R. 

 Japonica, is a beautiful large-leaved species, 

 forming a bush from six to ten feet high, and 

 commonly cultivated by the Japanese, who 

 plant it either with Azaleas and other bushes, 

 or singly, as it forms a beautiful object when 

 covered with its numerous bouquets of dark 

 crimson flowers. Hardy in the vicinity of 

 New York with slight protection. They are 

 propagated by seed. First introduced in 1664. 



Rha'pis. From rhapis, a needle ; referring to 

 the needle-like segments of the leaves. Nat. 

 Ord. Palmacece. 



A small genus of Palms, closely allied to 

 Chamcerops. They are nearly all natives of 

 Eastern Asia, and mostly of dwarf habit and 

 slender growth. One of the species, R.Jlabel- 

 liformis, is popularly known as Rattan Palm, 

 and furnishes the walking canes so common 

 on the streets. R. humilus, is a rare and beau- 

 tiful species, not often seen in collections, 

 and is propagated by suckers. First intro- 

 duced in 1765. 



Rhapo'nticum. From Rha, the old Greek name 

 for Rhubarb, and Ponticus, of Pontus. Nat. 

 Ord. Composites. 



A genus of annual or perennial herbs, one 

 or two of which are cultivated in full collec- 

 tions of hardy herbaceous plants. R. cyna- 

 roides, a species introduced from the Pyrenees, 

 growing three or more feet in height, has a 

 stout stem and large leaves, covered under- 

 neath with silvery down. R. pulchrum, 

 is another very showy species from the Cau- 

 casus. They are suitable plants for borders, 

 the margins of groups, or for isolation, and 

 are easily increased by division. 



Rhea. A name given to Bozhmeria nivea, and B. 

 utilis. 



Rhe'um. Rhubarb. From Rha, the Russian 

 name of the river Volga, near which the Rhu- 

 barb was found. Nat. Ord. Polvgonacece. 

 Some of the species of this well-known genus 



