Marsilia. MARSILIACE^E. 351 



spores (0.15 to 0.23 of a line wide) beset with minute points and wrinkles; micro- 

 spores (.013 to .015 of a line long) more or less papillose or spiuulose, deep brown. 

 Amer. Naturalist, viii. 214. 



Ponds and shallow lakes on the Sierra Nevada at 5,000 to 10,000 feet altitude, in several 

 places (Bolandcr) ; also near Yellowstone Lake, Parry. 



2. I. pygmaea, Engelm. 1. c. Deeply submerged, having few (5 to 10) short 

 (| to 1 inch long) stout rapidly tapering dark -green leaves, with very short ofteii 

 even square epidermis-cells, without stomata or bast-bundles : sporocarp circular with 

 a very narrow velum ; macrospores (0.18 to 0.25 of a line wide) marked with smaller 

 and more regular, rarely confluent, rather sharp points; microspores (.012 to .014 of 

 a line long) brown, very minutely papillose or almost smooth. 



In large patches in mud covering gravel, deeply submerged in running water, on the Mono 

 trail, eastern declivity of the Sierra Nevada, at 7,000 feet altitude, Bolander, 1866. Closely 

 allied to the last species, distinguished by its stout short leaves without stomata, the markings 

 of the larger macrospores, etc. ; in many respects near /. lacustris. 



I. NUTTALLII, Al. Braun, a terrestrial species, with triangular leaves 3 to 7 inches long, having 

 numerous stomata, the oblong sporocarp entirely covered by the velum, and the macrospores 

 minutely verrucose, occurs in Oregon and is to be sought for in Northern California. 



ORDER CXXIV. MARSILIACE-Si. 



Perennial plants rooted in mud, having a slender creeping rhizome and either 

 filiform or 4-parted long-petioled leaves ; the somewhat crustaceous several-celled 

 conceptacles borne on peduncles which rise from the rhizome near the leaf-stalks 

 or are more or less consolidated with the latter, and contain both macrospores and 

 microspores. 



The order consists of two genera of similar habit. In both the leaves or leaf-stalks are circulate 

 in vernation. The macrospores have a minute terminal papilla, which produces a small prothal- 

 lus bearing a few archegonia, fertilized by antherozoids formed within the microspores. 



1. MABSILIA, Linn. 



Conceptacles or sporocarps ovoid or bean-shaped, composed of two vertical valves 

 having several transverse compartments or sori in each valve ; the sori composed of 

 both macrosporangia and microsporangia. The sporocarps are provided with a ring, 

 which is the outer part of the vertical dissepiment, and which at the opening of the 

 valves swells up and becomes a mucilaginous filament, tearing the sori from their 

 places within the valves. Plants with peltately quadrifoliolate leaves on slender 

 petioles ; the sporocarps peduncled and rising either from the petiole or from the 

 rhizome at the base of the petiole. 



About 50 species are known, of which 5 or 6 occur in the United States. The plants commonly 

 grow in mud under shallow water and have floating leaves, but are sometimes terrestrial. In 

 many species the sporocarp has two short teeth near its insertion on the peduncle. 



1. M. vestita, Hook. & Grev. Leaflets broadly cuneate, usually hairy, entire, 

 2 to 7 lines long and broad ; petioles 1 to 4 inches long : peduncles free from the 

 petiole ; sporocarps solitary, short-peduncled, about 2 lines long, very hairy when 

 young ; upper tooth longest, acute, straight or curved ; lower tooth obtuse, the sinus 

 between them rounded. Ic. Fil. t. 159 ; Engelm. Amer. Journ. Sci. 2 ser. iii. 55 ; 

 Al. Braun, in Monatsb. Acad. Berlin, 1863, 423. M. villosa, Brackenridge, Ferns 

 of U. S. Expl. Exp. 340, as to the American plant. 



Collected in California by Dr. Pickering, and in upland soil at Brownsville, Yuba County, 

 A. Wood; Oregon to Texas. M. mucronata, Al. Braun, is a form of this species with longer 

 peduncles and less hairy sporocarps. 



