MARSILIACE^K. 3 



Rather sparingly but generally distributed from Cornwall and 

 Sussex, northwards to Skye and Sutherland. Rare in Ireland, where 

 it has been noticed in the west, and more plentifully in the 

 north-east. 



England, Scotland, Ireland. Perennial. Summer, Autumn. 



Rootstock long, creeping, filiform, sparingly branched, glabrous 

 except at the growing apex, which is clothed with hairs, producing 

 1 or more adventitious roots at each point from which leaves are 

 given off. Leaves 1 to 4 inches long, 2 to 4 together at intervals 

 along the rootstock, erect, deep green, smooth, with a few very minute 

 hairs or papillae, the young ones coiled up at the apex like the fronds 

 of a Fern. Sporocarps solitary in the axils of the leaves, very shortly 

 stalked, globose, slightly pointed, resembling small peppercorns, at 

 first hairy, at length glabrous, divided parallel to the axis into 4 cells, 

 with a parietal placenta running down each ; to this placenta the 

 sporangia are attached, forming a sorus. Lower sporangia in each 

 sorus a dozen or more, each containing a single macrospore ; upper- 

 most sporangia of the sorus containing numerous microspores : in 

 either case the sporangia are small thin hyaline walled sacs which 

 eventually burst and discharge their spores, which escape enveloped 

 in the jelly which fills the sporangia, and by its expansion causes 

 their rupture. Ripe microspores enveloped in a gelatinous coat, 

 furnished with a small projection at the apex, formed by the protrusion 

 of the inner layer of the spore, which is torn into shreds. Underneath 

 all this there is a collection of protoplasm, from which is developed 

 the prothallium ; for the details of this, see HofTmeister on the 

 Higher Cryptogamia, translated by Currie, pp. 318 to 324. 



Pillwort, or Pepper-grass. 



ORDER XC— I SOETACEiE. 



Aquatic or terrestrial plants consisting of a fleshy depressed 2- to 4- 

 lobed corm, producing simple or forked root-fibres, and giving rite 

 to rush-like leaves with dilated bases, which are sometimes per- 

 sistent. Leaves subulate or linear, containing 4 air-tubes, with 

 transverse partitions, furnished with stomata in some species. 

 Sporangia solitary, immersed in the inner face of the dilated base 

 of the leaves to which they are connected by their backs, crossed 

 internally by threads affixed to their upper and under sides ; the 

 sporangia of the outer leaves containing numerous macrospores, those 

 of the inner leaves containing very numerous microspores. Some 

 species have phyllodes, or barren leaves, on the corm between the 



B 2 



