74 ACOTYLEDONS. ALG/E. Nostoc. 



ORDER III. AIALE*. 



Vegetables for the most part aquatics, destitute of roots, or fur- 

 nished only with a fibrous or scutate base for the purpose of 

 attachment merely j whose fronds are either gelatinous, fila- 

 mentose, membranous, or coriaceous, having, for fructifica- 

 tion, seeds or sporules, either imbedded in tubercles or pro- 

 cesses arising from the frond, or immersed and more or less 

 scattered in the substance of the frond itself. 



Many species of this singular, and, generally speaking, beautiful 

 order of plants, frequently float in the water without any point 

 of attachment to extraneous substances. They are mostly 

 subpellucid, and the cellules are often elongated and united so 

 as to form fibres interrupted by transverse dissepiments. Their 

 colour is various, often green, brown, red, &c. After having 

 been kept dry for a great length of time, they will revive by 

 immersion in water, but that portion of the plant only imbibes 

 the fluid which is immersed in it. 



Div. I. TREMELLIN^:. Frojid gelatinous of a determined Jigure, 

 containing within conferva-like or beaded Jilaments. Root 

 none, frond either glolose or palmate, or Jiliform, consist- 

 ing of a gelatinous, pellucid substance, in which are imbedded 

 clustered, conferva-like, jointed, branched, or simple Jila- 

 ments. Fructif. either interior, included in the joints of the 

 Jilaments, or rarely exterior in capsules. Colour generally 

 green, sometimes brown or purplish. 



1. NOSTOC. 



Filaments moniliform, composed of united globules. Frond oli- 

 vaceous, between gelatinous and coriaceous, bullate, hollow, 

 at length spreading, filled with moniliform, simple, curved, 

 and crisped filaments. According to Vaucher, these plants 

 propagate by the globules of which the filaments are composed, 

 which, by degrees, separate and grow into new individuals. 



1. N. commune, upon the ground, frond lobed and plicate bul- 

 late gelatinous olive green. Ag. p. 133. Tremella Nostoc, 

 Lightf.p.WS. E.B. t.46l. 



HAB. Gravelly walks and pastures after rain, frequent, Light/. , HopJc. 



2. N. verrucosum, frond bladdery subcoriaceous hollow plicate 

 and smooth. Ag.p. 132. Tremella verrucosa, Lightf. p. 899. 



* In this order I follow and adopt the ordinal and generic characters, with 

 few exceptions, of Agardh, in his Synopsis Algarum ScandincwiG, Lund. 

 1817. 



