Division II. FLOWERLESS or CRYPTOGAMOUS PLANTS. 



Plants destitute of proper flowers ; producing (sometimes by two kinds of 

 organs) reproductive organs called spores, which differ from seeds in having 

 neither integuments nor embryo. 



Order CXXVI. EQUISETACEjE. DC. The Horsetail Tribe. 



Fructification in terminal cones or spikes, composed of peltate scales, which are 

 attached to a central axis, and bear on their inner surface several involucres 

 or thecse which contain the spores. The spores are attached to 4 club-shaped 

 elastic filaments (elaters) which roll up when moist, and uncoil themselves when 

 dry. — Leafless herbaceous perennial plants, with creeping rhizomas. Stems 

 hollow and jointed, striate, either simple or with whorled branches, and fur- 

 nished at the nodes with toothed sheaths, which may be regarded as united 

 whorls of leaves. The epidermis contains a large quantity of silex, which is 

 deposited in a singular and beautiful manner. The intervals between the 

 striae are perforated with stomata. 



1. EQUISETUM. Linn. ; Endl. gen. no. 601. horsetail. 



[From the Latin, cquus, a horse, and seta, a hair or bristle ; some of the species resembling a horsetail.] 



Character the same as that of the Order. 



An excellent account of the North American species of this genus, by Prof. Braun, with additions by Dr. Englemann, 

 is given in Silliman's Journal, Vol. 46. 



* Fertile stems unbrancked, discolored, appearing before the sterile ones. 



1. Equisetum arvense, Linn. Field Horsetail. 



Sterile. Stems erect or assurgent, roughish, with 12-14 furrows, the branches 3 - 4- 

 angled and ascending; teeth of the sheath lanceolate-subulate ; fertile stems simple, erect; the 

 sheaths large, loose, remote. — Linn. sp. 2. p. 1061 ; Engl. hot. t. 1874 ; Pursh, fl. 2. p. 

 651 ; Bigel. fl. Bost. p. 383 ; Torr. compend. p. 389 ; Beck, hot. p. 446 ; Darlingt. fl. 

 Cest. p. 573 ; Braun $ Engl. I. c. p. 83. 



