RHU 



The fecond, as the radius is to the half fum of the co- 

 fines of both latitudes, or (rather for geometrical fchemes) 

 as the diameter is to the fura of the co-lines of both latitudes 

 fo is the difference of longitude to the departure from the 

 meridian. For the application of thefe principles, fee 

 Sailing. 



RHUN, Pulo, in Geography. See Poolaros. 



RHUNE, a river which rifes in the New Forell, and 

 runs into the Seine ; two miles N.W. of Nordheim. 



RHUS, in Botany, an ancient name, poo;, or p'ou-;, of the 

 Greeks, generally fuppofed of doubtful etymology. De 

 Tlieis deduces this, and many fimilar words, which have 

 a reference to a red colour, from the Celtic rhudd or 

 rub, red. Plence, according to him, we have not only 

 Rubia, but Rofa. The fruit of the original pv; of Diof- 

 corides, Rhus Corlaria, well julUfies this explanation. — 

 Linn. Gen. 146. Schreb. 197. Willd. Sp. PL v. 1. 1477. 

 Mart. Mill. Did. v. 4. Sm. Prodr. Fl. Grac Sibth. v. 1. 

 206. Purfh 204. Ait. Hort. Kew. v. 2. 161. .lull. 369. 

 Lamarck Illutlr. t. 207. Ga:rtn. t. 44. — Clafs and order, 

 Penlandria Trigynia. Nat. Ord. Dumoft ? Linn. Terebln- 

 taceit, J u(l". 



Gen. Ch. Cal. Perianth inferior, of one leaf, in five 

 deep, erect, permanent fegments. Cor. Petals five, ovate, 

 moderately fpreading. Slam. Filaments five, very (hort ; 

 anthers fmall, fhorter than the corolla. Pijl. Germen fu- 

 pcrior, roundifh, as large as the corolla ; flyles fcarcely any ; 

 lligmas three, heart-lhaped, fmall. Peru. Berry roundifh, 

 of one cell. Seed folitary, roundifh, bony. 



Obf. Some fpecies have dioecious flowers. 



EfT. Ch. Calyx in five deep fegments. Petals five. 

 Berry fuperior, with one feed. 



An extenfive lhrubby ur arborefcent genus, whofe fpecies 

 are found 111 North America, Japan, China, the Cape of 

 Good Hope, and a few in the fouth of Europe. Their 

 qualities arc of a caultic nature, in certain inflances highly 

 virulent, whence fome fpecies have acquired the name of 

 Poifon-trees. Others are celebrated for producing valuable 

 relins for varnilh. Willdcnow has collected together the 

 characters of thirty-three fpecies ; but many of them he had 

 not feen, particularly thofe found by Thunberg at the Cape. 

 The genus is divided into three fed ions, by the ftrudure of 

 the leaves, of which we (hall give a few examples. Purfh 

 has two fpecies not in Willdcnow. Twenty-one are culti- 

 vated in the Englifh gardens. Alton. 



Sedion I. Leaves pinnate. Thirteen fpecies, to which 

 the two defcribed by Purfh are to be added ; fee here- 

 after. 



R. Corlaria. Elm-leaved Sumach. Linn. Sp. PI. 379. 

 Willd. n. 1. Ait. n. 1. Sm. Fl. Graec. Sibth. t. 290, un- 

 publifhed. Woodv. Med. Bot. t. 261. Ger. Em. 1474. 

 ( Rhus ; Matth. Valgr. v. 1. 195.) — Leaves pinnate ; leaflets 

 oval, bluntly ferratcd, downy beneath ; their common (talk 

 winged in the upper part. — Native of the Levant. Fre- 

 quent in our gardens and (hrubberies, ever fince the days of 

 Gerarde, (though lefs common than the American R. typhi- 

 num,) flowering in July, and retaining its denfe, branched, 

 ample, upright eluflers, of deep-red, rough, coriaceous ber- 

 ries, even till winter, after the leaves are fallen. The tree 

 is of a dwarf bufhy habit, with fpreading, afcending, round, 

 downy branches, of a foft fpongy texture. Leavci from 

 eight inches to a foot long, of about five pair of leaflets, 

 with an odd one ; paler, downy, and veiny beneath. Flowers 

 grecnifh, each with a large hoary germen, which becomes a 

 globular, crimfon, hairy berry, the fize of an Elder-ben y. 

 Thetalle of this fruit is very acid and aftringrnt. It has 



Vol. XXX. 



H H U 



be«ii uieJ in Greece, from the mod remote antiquity, for 

 tanning leather ; as have alfo the leaves, to the prefent day. 

 Both have likewife been employed 111 medicine, either for 

 their tonic or cooling qualities, nor do they appear to poflefs 

 any of the dangerous qualities for which fome fpecies of this 

 genus are remarkable. Dr. Woodville's figure of this plant 

 ought to have been quoted in Hort. Kew. as not cited bv 

 Willdcnow, and being moreover an Englifh publii it ... 



R. javatiicam. Java Sumach. Linn. Sp. PI. 380. 

 Willd. 11. 3. Ait. n. 3. Thunb. Jap. 121.- Leaves pinnate, 

 ovate, pointed, ferratcd ; very downy and foft beneath. — 

 Native of Japan, flowering in September. Introduced into 

 the lloves at Kew, by fir Jofeph Banks, in 1799. The 

 branches, and all thcflalhs, as well as the backs of the haves, 

 are clothed with extremely foft, denfe, velvet-like pubef- 

 cence, as is the upper iide ot the foliage in fome degree. 

 Each leaf has three pair, with an odd one, of ilalked, ovate, 

 taper-pointed leaflets, ftrongly ferratcd, and about an inch 

 and a half long. Flowers very fmall, in long, flender, lax, 

 fimple, axillary clufters. 



R. glabrum. Smooth Sumach. Linn. Sp. PI. 380. 

 Willd. 11. 4. Ait. 11. 4. Purfh 11.2. Kalm's Travels, v. 1. 

 66.75. ( R. virginicum, panicula fparfa, ranus patulis gla- 

 bris ; Dill. Elth. 323. t. 243. f. 3 14. ) — Leaves numeroufly 

 pinnate, lanceolate, ferratcd, fmooth on both fides ; glau- 

 cous beneath. — Common in North America, flowering in 

 July and Auguli, nor is it rare in our fhrubberies. Kalm 

 fays that ncgleded corn-fields are foon overrun with this tree, 

 whofe roots fubfequently render ploughing the ground very 

 difficult. The leaves confift of from eight to twelve pair of 

 longifh taper-pointed leaflets, fmooth and naked on both 

 fides. The fruit much refembles the firlt. fpecies in colour 

 and mode of growth, but is lefs hifpid. According to Mr. 

 Purfh, the R. elegans, Ait. Hort. Kew. n. 5. Willd. n. J, 

 is only a variety of this, with dioecious^owir.r, and a more 

 fcarlet-coloured fruit. 



R. vlrldiforum. Green-flowered Sumach. Lamarck 

 Did. v. 7. 504. Purlh 11. 3. (R. canadenfc; Mill. Did. 

 ed. 8. n. 5.) — Leaves numeroufly pinnate, ovato-lauceolatt, 

 ferrated ; glaucous, and fomewhat downy beneath. Clui- 

 ters ered. — On the edges of woods in dry funny fituations, 

 in Pennfylvania and Virginia, flowering in July and Auguft. 

 This is one of the fpecies added by Mr. Purfh, after Poiret 

 in Lamarck, but not without a donbt of its being diilind 

 from the laft. We can find no important difference in a 

 fpecimen from the French gardens, except that the leaflets 

 are rather more ovate. The flowers are yellowifh-green. 

 Leaves not always downy. 



R. pumilum. Dwarf Poifon Sumach. Michaux Borcal- 

 Amer. v. I. 182. Purfh 11. 4. — Leaves numeroufly pin. 

 nate, oval, fcarcely pointed, deeply toothed ; downy be- 

 neath. Branches and footltalks downy. Fruit clothed with 

 velvet down. — Native of Upper Carolina, flowering in 

 July. The Jtem is not above a foot high. This fpecies is 

 unknown in our gardens. Mr. I. Lyon, who gathered it, 

 allured Mr. Purlh, that it was the moll poifonous of the ge- 

 nus, he having been " poifoned all over his body, and lamed 

 for a confider lble time," in confequence of collcding the 

 feed. 



R. Venn. Varmfh Sumach. Linn. Sp. PI. 380. Willd. 

 n. 6. Ait. 11. 6. Purlh n. 5. Kalm's Travels, v. J. 68. 77. 

 (Toxicodendron, foliis alatia, frudu rhomboide ; Dill. 

 Elth. 390. t. 292. f. 377.) — Leaves pinnate, very linooth, 

 as will as the bran< lies ; leaflets elliptical, entire, fomewhat 

 abrupt, pointed. Chillers compound, lax. Flowers dioe- 

 cious. Fruit polifhcd.— Found in low copfes, from Cana- 

 da to Carolina, flowering in July. Pur/lj. It has been in 

 B b our 



