476 SELAGINELLACEAE. 



2. Marsilea vestita Hook. & Grev. Ic. Fil. pi. 159. 1831. 



Eootstock slender. Petioles slender, 5-13 cm. high; leaflets entire or 

 toothed; sporocarps 48 mm. long, 4-6 mm. wide, with a short raphe, a short 

 and blunt lower tooth and an acute and sometimes curved upper one, densely 

 covered with soft spreading narrow hair-like scales; sori 6-11 in each valve. 



Wet sandy soil, Acklin's Island and South Caicos : southern and western United 

 States. The Bahama specimens are sterile and are referred to this species with 

 doubt. HAIRY PEPPEIRWORT. 



Order 3. LYCOPODIALES. 



Spores produced in sporanges, which are borne in the axils of scale- 

 like or elongated leaves. 



Spores all alike. Fam. 1. PSILOTACEAE,. 



Spores of two kinds. Fam. 2. SELAGINELLACEAE. 



Family 1. PSILOTACEAE Pritzel. 



PSILOTUM FAMILY. 



Perennial slender terrestrial or epiphytic plants. Sporanges sessile 

 in the axils of the leaves, 2-3-celled, opening by valves at the apex. 

 Spores uniform. Only the following genus, and the monotypic Tmesipteris 

 of Australasia. 



1. PSILOTUM Sw. in Schrad. Journ. Bot. 1800 2 : 109. 1801. 



Terrestrial or sometimes epiphytic, the stem dichotomously forked. Leaves 

 alternate, reduced to scales. Sporanges 3-celled, .opening by 3 valves at the 

 apex. Spores mealy, oval or elongated-reniform. [Greek, referring to the 

 nearly naked stems and branches.] A few species of tropical and subtropical 

 distribution, the following typical. 



1. Psilotum nudum CL.) Griseb. Veg. Kar. 130. 1857. 



Lycopodium nudum L. Sp. PI. 1100. 1753. 



Psilotum triquetrum Sw. in Schrad Journ. Bot. 1800 2 : 109. 1801. 



iStems erect, 2-3 dm. tall, or, when in caves or on trees, often pendent, 

 3-angled at the base, copiously forked, above, the ultimate divisions with 3 

 wing-like angles; leaves remote, awl -like, less than 2 mm. long; sporanges in 

 interrupted spikes. 



On tree-trunks and in sink-holes, Abaco, New Providence, Andros, Cat Island, 

 Great Exuma : Florida ; Bermuda ; West Indies ; continental tropical America and 

 Old World tropics. PSILOTUM. 



Family 2. SELAGINELLACEAE Underw. 



Terrestrial, annual or perennial, moss-like plants with branching stems 

 and scale-like leaves, which are many-ranked and uniform, or 4-ranked and 

 of two types spreading in two planes. Sporanges 1-celled, solitary in the 

 axils of leaves which are so arranged as to form more or less quadrangular 

 spikes, some containing 4 macrospores (macrosporanges), others contain- 

 ing numerous microspores (microsporanges), which develop into small 

 prothallia, those from the macrospores bearing archegones, those from the 

 microspores antherids. The family consists of the following genus : 



