Plate V. 
Fig. 17. DESMARESTIA LIGULATA. 
Colour, When growing, a clear olive-brown ; on exposure to the atmosphere, a verdigris- 
green ; when dry, sometimes yellow ; sometimes a pleasant green ; semi-transparent. 
Substance. Delicately membranaceous. Becoming limp {flaccid) after exposure to the air. 
Eecovering itself when dry. 
Character of Frond. Flat ; with an obscure midrib towards the base ; branched. Branching 
on each side of the stem ; the branches branched again and again (repeatedly 
Branches and branchlets in pairs exactly opposite each other, and all tapering at 
each end. The whole frond at one level as if cut out of paper {distichous). In youth 
the margins of the branches are fringed with minute tufts of cobweb-like fibres, 
which fall off as the plant advances in age. 
Measurement. From 2 to 6 feet long ; width varies very much, 
Fructification. Not ascertained. 
Habitat. South of England ; occasionally north-east (Filey). All round the coast of Ireland. 
Between tide-marks, on rocks and stones. 
In the north-west of Ireland a variety occurs, which is sometimes from I to 2 inches 
wide ; called D. Dresnaii by French botanists. 
Fig. 18. DESMAEESTIA ACULEATA. 
Colour. When fresh and young, stems green olive ; tufts bright green ; on exposure to the 
atmosphere, verdigris-green ; when dry, resuming its original hues. In age, brown. 
Substance. Tender and membranaceous in youth. Becoming limp and sticky on exposure to 
the air. Recovering itself when dry. In age, harsh. 
Character of Frond. Stem and branches. Stem very short ; cylindrical. Branches long ; very 
narrow ; slender ; flat ; repeatedly rebranched. Margins, in youth, fringed with 
minute tufts of delicate bright green fibres ; in age, with thorns. 
Measurement. From 1 to 3 feet long. 
Fructification, Not ascertained. 
Habitat, Our coasts generally. On rocks near low-water mark ; common. 
A beautiful plant when young, from the bright green tufts which fringe its margins ; but 
ugly when old. All three Desmarestias should, during collection, be kept apart from delicate red 
sea-weeds, as they possess some curious power of decomposing their more fragile neighbours. 
9 o 
