RHAMNACEAE 
553 
(rarely 2) basal ovule with downwardly-directed micropylc. Style 
simple or divided. Fruit dry, splitting into dehiscent or indehiscent 
mericarps, or a drupe with 1 or several stones, or a nut. Endosperm 
little or none. Many of the dry fruits show special adaptations for 
wind-carriage, e.g. Paliurus, Ventilago. The order is closely related 
to Vitaceae, from which it is chiefly distinguished by the small petals, 
the receptacle, the endocarp and simple leaves; it also approaches 
Celastraceae, the chief distinction being the antepetalous sta. Chief 
genera: Ventilago, Paliurus, Zizyphus, Rhamnus, Hovenia, Ceano- 
thus, Phylica, Colletia, Gouania. Few are of economic value; see 
Zizyphus, Rhamnus, Hovenia. Benth. -Hooker place the order in 
Celastrales, Warming in Frangulinae. 
Rhamnales. The 21st cohort of Archichlamydeae (p. 129). 
Rhamneae (Benth. -Hooker) = Rhamnaceae. 
Rhamnus Tourn. ex Linn. Rhamnaceae. 70 sp. N. temp., a few trop. 
and S. temp., 2 in Brit., R. cathartica L. the common or purging 
buckthorn, and R. Frangula L., the Alder buckthorn. The R. are 
shrubs with alt. or opp. leaves and small cymose clusters of firs. 
The genus is divided into two sections. To § 1, Eurhamnus (firs, 
usually 4-merous, polygamous or dioecious), belong R. Alaternus L. 
(Medit.) and R. cathartica (Eur., As., Medit.), whose berries possess 
active purgative properties ; the juice of the fruit is mixed with alum 
and evaporated, thus forming the paint known as sap-green; also 
R. infectoria L. (Mts. of S. Eur.) whose berries are known as Graines 
d’ Avignon or ‘yellow berries’ and yield useful green and yellow 
dye-stuffs, and R. chlorophora Dene, from whose bark the Chinese 
prepare the dye known as ‘ Chinese green indigo * used in dyeing silk 
(R. utilis Dene, is also employed). To § 2, Frangula (firs, usually 
5-merous, $ ), belong R. Frangula (Eur., As., N. Afr.) whose bark is 
officinal (cathartic) and whose wood forms one of the best charcoals 
for gunpowder, R. Purshiana DC. in N. Am., whose bark (Cascara 
sagrada) is largely used as a cathartic. 
Rhaphidophora Hassk. Araceae (11). 25 sp. E. Ind. Plants with 
sympodial climbing stems with clasping roots and pendulous aerial 
roots. The pinnation of the leaves arises by a process similar to that 
which occurs in Monstera, i. e. by long holes arising between the ribs, 
and the margin finally breaking. Firs. $ . 
Rhapis Linn. f. Palmae (1. 2). 5 sp. E. As. 
Rheum Linn. Polygonaceae (1. 2). 20 sp. temp, and subtrop. As. 
The firs, are like those of Rumex, but are coloured and entomo- 
philous, though they exhibit traces of anemophilous nature in their 
very large stigmas (cf. Poterium &c.). R. officinale Baill. furnishes 
medicinal rhubarb; R. Rhaponticum L. is the rhubarb used as a 
vegetable. 
Rhexia Linn. Melastomaceae (1). 7 sp. East U.S. 
Rhinanthus Linn. (incl. Fistularia Linn.). Scrophulariaceae (ill. 12). 
