126 OUR NATIVE FERNS AND THEIR ALLIES. 



of microspores. Named from Gr. a^eiv, to dry, and oWvuai, 

 to destroy. Includes five species. 



1. A. Caroliniana Willd. Plants f — i' long, reddish or 

 greenish; cuticle of macrospores finely granulate; masses of mi- 

 crospores with rigid septate processes. New York to Florida, 

 Arizona and Oregon. 



2. A. filiculoides Lam. Fronds i' — 2' long, often erect- 

 crowded ; cuticle of macrospores with large discoid tubercles ; 

 masses of microspores with rigid processes without septa. La 

 Honda, California, and possibly widely distributed in that state 

 since most of the material recently collected in California ap- 

 pears to be this species. The plants often grow in densely 

 crowded masses and are usually much larger than the 

 Eastern species. 



The order Equisetales contains only a single family made 

 up of rush-like plants often growing in wet places or in sand. 



Family 1. EQUISETACE>^ DC. 



Plant- body rush-like, often branched, with jointed, usually 

 hollow stems rising from subterranean rootstocks, the sterile 

 leaves reduced to sheaths at the joints, the fertile forming a 

 short spike terminating the stem. Prothallium above ground, 

 green, variously lobed, usually dioecious. Represented at pres- 

 ent by only one genus. 



I. EQUISETUM L. Horse-tail. Scouring-rush. 



Perennial plants with extensively creeping rootstocks. Stems 

 simple or branched, furrowed lengthwise, hollow, and pro- 

 vided with an outer circle of smaller cavities opposite the fur- 

 rows as well as a second and smaller series opposite the ridges. 

 Sporangia adhering to the under side of the shield-shaped 

 scales of the spike, one-celled, opening down the inner side. 

 Spores furnished with two slender filaments attached by the 



