472 MARSILEACEJE. [PILULARIA. 



Sandy soil, inundated at times, Guernsey ; frt. May-June. Com short, 

 stout, subglobose, 1 in. diam., clothed with the old spinescent dark 

 horny leaf -bases, which consist of lateral subulate processes, and an inter- 

 mediate tooth. Leaves 1-2 in., slender, plano-convex, obscurely tubular, 

 sheath enveloping the capsule. Mao-ospores white. DISTKIB. S. Europe, 

 N. Africa. 



ORDER III. MARSILEA CEJE. 



Aquatic plants of various habit. Rootstock or stem creeping. Leaves 

 filiform or bearing 4 obovate leaflets ; vernation circinate. Fructification 

 of 2- or more-celled coriaceous oblong or globose capsules (formed of a meta- 

 morphosed leaf; placed near or on the rootstock, and containing on parietal 

 placentas many membranous sacs, enclosing macrospores and microspores. 

 DISTRIB. Temp, and trop. regions ; genera 2 ; species 40. AFFINITIES. 

 With Lycopcdiaceae. 



In germination the macrospores develop a prothallus, the archegonia 

 of which are fertilized by the contents of the microspores, as in Lyco- 

 podiacece. 



1. PILULA'RIA, L. PlLLWORT. 



Rootstock filiform, creeping. Leaves subsolitary, erect, setaceous. Cap- 

 sules globose, 2-4-celled, 2-4-valved at the top ; cells each with a longi- 

 tudinal parietal placenta, on which are inserted many pyriform mem- 

 branous sacs ; sacs in the upper part of the cell full of microspores im- 

 mersed in mucilage ; those in the lower part contain each one macrospore. 

 Microspores globular, full of antherozoids. Macrospores ovoid, with an 

 outer coat of prismatic cells, pierced by a funnel-shaped opening, through 

 which an inner glassy coat finally protrudes. DISTUIB. N. and S. temp. 

 and cold regions ; species 3. ETYM. pilula, from the form of the capsule. 

 In germination a prothallus is developed at the top of the protruded 

 portion of the inner coats of the macrospore, which bursts and frees it. 

 After expulsion an archegonium is formed on the prothallus, and fertili- 

 zation takes place by the contents of the microspore. 



1. P. jrlobulif era, L.; leaves setaceous, capsules pubescent. 

 Edges of lakes and ponds, from Skye and Sutherland southwards ; N. E. and 

 W. of Ireland, very rare; frt. June- Aug. Rootstock or stem 2-6 in., 

 glabrous, cylindric. Lewes 2-4 in., green. Capsules ^ in. diam., ovoid or 

 globose, shortly pedicelled, in the axils of the leaves or on the rootstock, 

 pubescent, brown, 4-celled. DISTRIB. Europe N. of the Alps. 



ORDER IV. EQUISETACE^E. 



Rootstock creeping. Stems erect, terete, jointed, grooved, hollow except 

 at the joints, and with air-cells in their walls under the grooves, joints 

 terminating in toothed sheaths ; teeth corresponding with the ridges ; 

 branches if present arising from the sheath-bases, solid. Capsules 6-9, 

 1-celled, on the under surface of the peltate scales of a terminal cone. 

 Spores of one kind, attached to 4 clubbed elastic threads (elaters), which 

 are coiled round the spore when moist, and uncoil when dry. DISTRIB. 

 Chiclly temp. N. regions, a few are sub-trop. ; none ara high southern ; 



