154 THE VOYAGE OF H.M.S. CHALLENGER. 



POLYGONACE^E. 

 Rumex frutescens, Thouars. (Plate XXX.) 



Rumex frutescens, Thouars, Esquisse Fl. Trist., p. 38; Carmich. in Trans. Linn. Soc. Lond., xii. 

 p. 50G ; DC, Prodr., xiv. p. 72. 



Tristan da Cunha and Inaccessible Island. Thouars; Carmichaei ', ; Moseley. 

 Endemic in these islands. Common all along the cliffs. 



EMPETRACE^E. 



Empetrum nigrum, Linn., var. rubrum. 



Empetrum nigrum, Linn., Sp. PL, ed. 1, p. 1022, var. rubrum. 



Empetrum rubrum, Yahl in Willd. Sp. PI., iv. p. 713 ; Hook, f., Fl. Antarct., ii. p. 345; Gay, Fl. 



Chil., v. p. 350 ; Thouars, Esquisse Fl. Trist, p. 39. 

 Empetrum medium, Carmich. in Trans. Linn. Soc. Lond., xii. p. 508. 



Tristan da Cunha, Inaccessible Island, Nightingale Island. Thouars ; Car- 

 michaei; Milne and MacGillivray ; Moseley. 



South Chili ; Fuegia ; Falkland Islands. 



Whether Ave regard this as a variety of the northern Empetrum nigrum (which is 

 diffused all round the northern part of the temperate zone, as well as the Arctic zone), or 

 as an independent species, its distribution is equally interesting. It is the only uuder- 

 shrub growing gregariously in the Tristan da Cunha group, where it is very abundant 

 and where it finds its eastern limit. 



MONOCOTYLEDONES. 



JUNCACE^E. 

 Juncus tristanianus, Hemsl. 

 June/as tristanianus, Hemsl. 

 Species, ut videtur, Junco bufonio valde affinis, differt culmis elongatis filiform i bus 

 (aphyllis ?) bracteolis minus scariosis, perianthii segmentis inter se sequalibus, seminibus 

 utrinque obtusis, &c. 



Tristan da Cunha. — Endemic. Boggy pastures — MacGillivray. 



The specimens of this rush are very incomplete, but the culm and inflorescence are 

 unlike any other species we have seen of the group to which it belongs. Each flower is 

 subtended by two bracteoles within the bracts, and the long, pointed segments of the 

 perianth are very much like those of Juncus bufonius, of which we at first thought it 

 might be an extreme form. There are no leaves, and the portions of the very slender 

 terete culms are about a foot long, with a terminal inflorescence not unlike that of the 

 robust Juncus bufonius. 



