955 



K\)t &rea£urg of SSotaug. 



[raff 



RADICELLA. A very small root ; the 

 young tiny root which appears from the 

 lower part of a young plant at the period 

 of germination. 



RADICIFORM. Being of the nature of 

 a root. 



RADICLE, RADICTJLA. The first root 

 of a plant, rudimentary in the embryo. 

 RADICOSE. Having a large root. 

 RADII. The peduncles of secondary 

 umbels, or of the flowers of simple umbels. 

 — iMEDULLARES. The medullary rays. 



RADIOLA. A genus of Linacece, differ- 

 ing from Linum only in the sepals, petals, 

 and stamens being four each, in the se- 

 pals being deeply trifld, in the stamens 

 ! being quite distinct, and in the capsule 

 ! bein? eight-celled. R.Millegrana, which is 

 I indigenous to England and the Continent, 

 is a very small annual, having a much- 

 1 branched stem, with opposite leaves, and 

 minute white flowers. [B. C] 



RADIS. (Fr.) Raphanus. — PETITE- 

 RAVE. Raphanus sativus. 



RADISH. The well-known esculent root 

 of Eaphanus sativus. — , HORSE. Coehlea- 

 ria Armoracia. — , SEA. Eaphanus ma- 

 ritimus. — , "WATER. Nasturtium amphi- 

 bium. — ."WILD. Raphanus Raphanistrum. 



RADIUS. The circumference or outer 

 side of the circle formed by umbels or 

 capitules or of other such parts. 



RADIX. The root; the descending axis; 

 that part which is the development of a 

 radicle. It differs from a stem not only in 

 its origin, but in not branching symmetri- 

 cally, and having no normal leaf-buds. 



RADULA. A genus of Jungermanniacea} 

 which is noticed here as containingB.com- 

 planata, a species common in woods on 

 almost every tree. The lobe at the under- 

 side of the leaves is remarkable for sending 

 roots into the substance on which it grows. 

 It belongs, like Madotheca, in which the 

 lobes are without radicles, to the division 

 Platyphyllce. [M. J. B.] 



RAEE, RAI. Indian names for Mustard- 

 seed, Sinapis nigra, S. ramosa, &c. 



RAFFLESIACE.E. {Rafflesiads.) A small ; 

 order of parasitical plants, the position j 

 of which in the natural system has been I 

 the subject of considerable difference of i 

 opinion, but which Lindley places amongst 

 Rhizogens. The plants which compose it 

 have no stem, but consist of flowers only, 

 sometimes of gigantic size, surrounded by 

 a few scales, and sessile on the stems or | 

 rhizomes of woody or perennial plants. \ 

 These flowers consist of a campanulate 

 or globular five-cleft perianth, with nu- 

 merous anthers on a central column. The 

 ovary is inferior, one-celled, with many- 

 seeded parietal placenta?, and as many 

 styles as placentae, more or less united 

 within the column, where the flowers are 

 hermaphrodite, or in the centre of female 

 flowers. The fruit is indehiscent, with nu- 



merous seeds, and the embryo undivided, I 

 with or without albumen. The principal 

 genera are Rafflesia and Brugmansia in 

 tropical Asia, and Pilostyles and Apodanth.es 

 in South America* 



RAFFLESIA. The name of a genus of 

 parasitical plants, natives of Java and 

 Sumatra. The species have great interest, 

 both for the botanist and for the general 

 public, owing to their peculiar structure 

 and appearance. The Eafflesias were first 

 made known in 1818. Sir Stamford Raffles, 

 at that time Governor of Bencoolen,was on 

 a tour in the interior of Sumatra, acconir 

 panied by Lady Raffles, Dr. Arnold, and 

 others, when the party lighted upon a 

 flower of enormous size, more than a yard 

 across. Descriptions and drawings of this 

 vegetable prodigy were sent to this coun- 

 try, and the plant was named by the cele- 

 brated Robert Brown, in honour of its dis- 

 coverers, Rafflesia Arnoldi. Since then 

 several other species have been discovered, 

 but none of equal size with that just men- 

 tioned, which indeed still retains its cha- 

 racter as being the largest flower known. 

 The genus, with one or two allies, is now 

 comprised in a distinct family, Rafflesiaceee. 



The true Rafflesias have no proper stems 

 or leaves, but consist solely of flowers, 

 varying in diameter from two or three 

 inches to as many feet, enveloped at the 

 base by a few bluish or brownish scales, 

 and emerging from the roots and trunks 

 of various species of Cissus. The unex- 

 panded flower-buds in R. Arnoldi are round- 

 ish, and resemble a close cabbage in shape. 

 The flowers appear to be dioecious, and 

 have a perianth which is tubular below, 

 but whose limb is divided into five entire 

 fleshy lobes, which partially overlap one 

 another in the bud, but afterwards spread 

 widely. The perianth is flesh-coloured and 

 mottled, and has a foul odour of tainted 

 meat, by which insects are attracted. 

 "Within is a thick fleshy rim or corona lin- 

 ing the upper part of the tube ; and within 

 this corona, in the male flowers, and occu- 

 pying the centre, is a thick fleshy column, 

 adherent to the perianth-tube, having one 

 or more projecting rims surrounding its 

 base, and at the top a wide flat plate, 

 the overhanging margin of which is rolled 

 round like the capital of an Ionic column. 

 On the revolute margin is placed a ring of 

 anthers, which are sessile, each one open- 

 ing by a single pore, although it is divided 

 in the interior into many compartments; 

 the pollen-grains are round. In the female 

 flowers, the deep cup-shaped perianth and 

 corona are like those of the male flowers ; 

 the central column is also similar, but 

 there are no anthers. The ovary is ad- 

 herent to the base of the tube of the pe- 

 rianth, has a single compartment contain- 

 ing numerous ovules attached to its walls, 

 and is surmounted by several styles, which 

 are blended with the central column. 



Three or four species are known, differ- 

 ing greatly in size, but little in essential 

 characters. The corona and summit of 

 the column are in some species studded i 



