5 6 4 
ROUP ALA 
Roupala Alibi. Proteaceae (n). 39 sp., 1 in Austr., 2 in New Caled., 
the rest in trop. Am. 
Rourea Aubl. Connaraceae. 40 sp. trop. 
Roxburghia Banks = Stemona Lour. 
Roxburgbiaceae (Benth. -Hooker) = Stemonaceae. 
Roydsia Roxb. Capparidaceae (iv). 3 sp. Indo-mal. 
Royena Linn. Ebenaceae. 13 sp. Afr. R . lucida L. yields useful 
timber. 
Rubia (Tourn.) Linn. Rubiaceae (11. 21). 5 sp. Eur., As., Afr., S. 
Am. (1 in Brit.). R. tinctorum Ii is the madder, formerly largely 
cultivated for its dye (alizarin), which is now prepared artificially. 
Rubiaceae. Dicotyledons (Sympet. Rubiales). 350 gen. with 4500 sp. 
forming one of the largest orders of plants. Most are trop., but a 
number (esp. of the Galieae ) are temp., and Galium itself has a few 
arctic sp. Trees, shrubs and herbs with decussate stip. entire or 
rarely toothed leaves. The stipules exhibit great variety of form; 
they stand either between the petioles (inter petiolar) or between the 
petiole and the axis (intrapetiolar). They are frequently united to 
one another and to the petioles, so that a sheath is formed round the 
stem. The two stipules — one from each leaf — that stand side by side 
are usually united, and in the Galieae, to which the Brit. sp. belong, 
are leaf-like, and often as large as the ordinary leaves; a character- 
istic appearance is thus produced, the plants seeming to have whorls 
of leaves ; and it is only by noting the axillary buds that a clue is 
obtained to the real state of affairs. The number of organs — leaves 
and stipules — in a whorl varies from 4 upwards, according to the 
amount of ‘fusion’ or ‘branching’ of the stipules. The simplest case 
is a whorl of 6, each leaf having 2 separate stipules ; if the stipules be 
united in pairs, a whorl of 4 results ; if each stipule be branched into 
two, we get a whorl of 10, and, if the centre pair of half-stipules on 
either side be united, a whorl of 8, and so on. 
Several R. are myrmecophilous (p. 115, and cf. Cecropia, Acacia), 
e.g. Myrmecodia, Cuviera, Duroia, 0 
Hydnophytum. 
The infl. is typically cymose. Soli- 
tary terminal firs, are rare ; small 
dichasia are more frequent ; the most 
common case is a much branched 
cymose panicle. 
The fir. is usually $ , regular, 
epigynous, 4- or 5-merous. K 4 — 5, 
epigynous, often almost absent, usually 
open in aestivation, sometimes with 
one sepal larger than the rest and 
brightly coloured (Mussaenda, &c.) ; 
Floral diagram of Asperula, 
after Eichler. 
