452 



MARCHANTIACEAE. 



portion splitting irregularly into from four to eight teeth; cells of wall with 

 numerous ring-like thickenings. [Commemorates B. C. Dumortier, born 1797, 

 a student of Hepaticae.] Three recognized species, especially of tropical 

 regions, the following typical. 



1. Dumortiera hirsuta (Sw.) 

 Eeinw. Bl. & Nees. DUMORTIERA. 

 (Fig. 497.) Thallus dark green, 

 mostly 4"-10" wide and 2'-4' long, 

 flat, slightly undulate along the mar- 

 gin. Inflorescence dioecious; spores 

 brownish, 22-30 n in diameter, thickly 

 tuberculate or papillose. [Marchantia 

 hirsuta Sw.] 



On wet rocks. Originally collected 

 by Moseley. Church Cave, E. G. Brit- 

 ton, M. A. Howe. A large species, re- 

 stricted to very wet localities. Widely 

 distributed in tropical regions ; also in 

 western and southern Europe and in the 

 eastern United States. 



4. MARCHANTIA L. 



Thallus branching dichotomously. Air-chambers with distinct boundaries, 

 forming a single layer ; green cells in short, simple or branched filaments rising 

 from the floors of the chambers, the filaments mostly three or four cells long ; 

 epidermal pores bounded by several superimposed layers, each usually com- 

 posed of four cells. Ventral scales variable, some divided into a basal 

 portion and an appendage. Inflorescence dioecious. Antheridial receptacle 

 terminal on a thallus-braneh, flat or slightly convex, more or less lobed, borne 

 on a somewhat elongated stalk with, two rhizoid-furrows. Carpocephalum 

 arising from the extremity of a thallus-braneh, composed of a flat or convex 

 central portion from which four to ten lobes radiate, often unsymmetrically, 

 the lobes flat or grooved underneath; stalk with two rhizoid-furrows; arche- 

 gonia (and sporophytes) in radiating groups between the lobes, each group 

 enclosed by a membranous involucre consisting of two folds with fringed 

 margins; pseudoperianth (around each sporophyte) tubular, membranous, with 

 an open, irregularly cleft mouth. Capsule without a lid, splitting into from 

 four to eight irregular teeth; cells of wall with ring-like thickenings. Gemmae 

 like those of Lunularia, borne in circular, cup-like conceptacles. [In honor of 

 Nicolas Marchant, director of the ducal garden at Blois, died 1678.] About 

 50 species, mostly tropical, the following typical. 



