RUTACEAE 
567 
Recent investigations (cf. review in Bot. Centr. ioi, p. 363) seem 
to show that R. is a genus in which the continual production of new 
forms, by mutation and by hybridisation, is going on (p. 115). 
Rudbeckia Linn. (excl. Lepachys Rafin.). Compositae (v). 30 sp. N. Am. 
Rudgea Salisb. Rubiaceae (11. 15). 100 sp. trop. Am. Some are 
heterostyled. 
Ruellia Plum, ex Linn. Acanthaceae (iv. A). 200 sp. trop. arid sub- 
trop. The capsule explodes. The seeds possess surface hairs which, 
when wetted, swell and adhere to the soil. 
Rumex Linn. Polygonaceae (1. 2). 100 sp. esp. in N. Temp, zone (12 
British, of which several, known as docks and sorrels, are among our 
commonest plants). Firs, of the type usual in the order, wind-fertilised, 
with large stigmas (see order for diagram, and cf. Rheum). R. Hydro- 
lapathum Huds. is said to produce aerating roots like a mangrove 
(p. 1 61). The roots of R. hymcnosepalus Torr. (N.W. Am.), the 
Canaigre, are used for tanning. 
Rungia Nees. Acanthaceae (iv. 13). 20 sp. trop. As. and Afr. 
Ruppia Linn. Potamogetonaceae. 1 sp., R. mciritima L., in salt or 
brackish water, temp, and subtrop. A slender swimming plant, with 
the habit of a small-leafed Potamogeton. The flrs. are borne just 
at the surface of the water, where fertilisation occurs by pollen 
floating upon the surface. Each spike consists of 2 flrs. not enclosed 
in the spathe at the flowering time. The flr. has 2 sta. with small 
outgrowths from the connectives, and four cpls. 
Ruprechtia C. A. Mey. Polygonaceae (ill. 6). 20 sp. S. Am. 
Ruscus (Tourn.) Linn. Liliaceae (vn). 3 sp. Medit., Eur. R. acn - 
leatus L. , butcher’s broom, in Brit., a small shrub. In the axils of 
scaly leaves stand leaf- like phylloclades ; half-way up each is another 
scaly leaf, in whose axil stands the flr. Fruit a berry. [Cf. Asparagus 
and Semele.] 
Russelia Jacq. Scrophulariaceae (11. 6). 6 sp. Mexico, Chili. R.juncea 
Zucc. is often cultivated in greenhouses. It is a xerophyte with 
much reduced leaves and pendulous green stems. Shoots sometimes 
appear under cultivation with broad leaves (perhaps a reversion to an 
ancestral type). 
Ruta (Tourn.) Linn. Rutaceae (11). 50 sp. Medit., As. R. graveolens 
L., the rue, is commonly cultivated in Brit. It is a strongly smelling 
shrub owing to the presence in the leaves, &c., of an ethereal oil. 
The terminal flr. of the infl. is 5-merous, the lateral flrs. 4-merous. The 
sta. lie in pairs in the boat-like petals; one by one they bend up- 
wards over the stigma, dehisce and fall back ; when all have done 
this, the stigma ripens, and finally the sta. again move up and effect 
self- fertilisation. The dirty-yellow strongly-scented flrs. are chiefly 
visited by small flies. Rue is employed in medicine as a narcotic and 
stimulant. 
Rutaceae. Dicotyledons (Archichl. Geraniales). 100 gen. with 800 sp. 
