23 
LITERATURE. 
All the species iii Ophioglossaceee within our limits are figured 
in Eaton's “Ferns of North America,” and outline drawings of 
most are contained in Knobel’s “Ferns and Evergreens of New 
England.” 
FAMILY III, EQUISETACE/E DC. 
R USH-LIKE plants, often branched, with grooved and jointed 
stems, the joints sheathed. Fruit a terminal spike ; spores 
all alike, furnished with four club-shaped filaments, (ela- 
ters), which curl around them spirally when moistened, but uncoil 
quickly when dry. 
EQUISETUM L. 
/ 
184. E. arvense (L.) Common Horsetail. Stems of two 
kinds ; the fertile 5-10 inches high, rather stout, pale brown, sel- 
dom branched, with loose and distant sheaths, soon perishing ; 
spike |-2 inches in length ; sterile stems later, more slender, us- 
ually caudate, with copious four-angled branches. Common every- 
where, especially in gravelly soil. Late April and early May. 
North temperate zone of both hemispheres. 
Figured in Wood’s “Botanist and Florist.” 
