99. EQUISETUM. 17 



roundish or suboblong, transversal, superficial pore. Tracheide bundles 

 enclosed by a common outer and a common inner endodermis (the 

 inner endodermis sometimes wanting, but not in Malayan material). 

 - Engl. & Prantl, 1. c., fig. 329. 



2. EU EQUISETUM. Stomata with their aperture on the level of the 

 epidermis, recognizable by a linear, longitudinal, superficial pore. 

 Tracheide bundles enclosed by a common outer endodermis, or rarely 

 by an own endodermis. (Not in Malaya). 



1. HIPPOCHAETE. 



* Ribs of the sheaths rounded. (1) E. ramosissimum. 



* Ribs of the sheaths flattened, angular at the sides. (2) E. debile. 



(1) E. ramosissliiium, Vest'., Milde, Mon. Eq., 428, tab. XXIV; 

 Bk., Fern All., 4 ; E. ramosum, Schleich., Schk., Krypt. Grew., I, tab. L72 b. 



Barren and fertile stems alike, solitary to caespitose, varying from 

 short to 3 m. or more long, 1 10 mm. diam., with a large central 

 hollow (V-2 2 /s diam.), grooved, simple or irregularly branched; branches 

 very different in length, few to numerous, simple or branched again ; 

 ribs 4 26, convex, narrower than the grooves, rough (transversely rugose 

 or verrucose) ; grooves provided with 2 separate or contiguous series of 

 stomata (each series consisting of 1 4 lines of pores). Sheaths loose, 

 distinctly funnel-shaped, relatively long, the teeth deciduous, with a per- 

 sistent, generally triangular-oblong base, the mouth of the sheaths there- 

 fore finally commonly toothed ; ribs convex at least in the upper part, 

 often striated with 1 or more fine and shallow furrows, the base passing 

 gradually into a rib of the stem. Spikes to 2Yz cm. long, acute or api- 

 culate. 



Nearly cosmopolitan. 



(2) E. debile, Kft., Milde, Mon. Eq., 476, tab. XXVI; Bk., Fern 

 All., 5; E. Timorianum, Vauch., Mon. Prel., 376, tab. X. 



Barren and fertile stems alike, solitary to caespitose, varying from 

 short to long, usually under TA m., rarely to 9 m. long, 2 15 mm. 

 or more diam., with a large central hollow ( 4 /s or more diam.), grooved, 

 FERN ALLIES. 2 



