The Flora of the Cayuga Lake Basin 37 



d. Teeth on the main stem black, moderately firm, scarcely cohering; fertile 

 stems unbranched (except in one form), soon perishing; sterile stems 

 obscurely excurrent, the branches ascending, subsimple, rather straight ; 

 silica in scattered dots. 1. E. arvense 



d. Teeth on the main stem light brown, subscarious, cohering in broad lobes ; 

 fertile stems at length sparingly branched and persisting ; sterile stems 

 strongly excurrent, the branches fine, irregular, drooping, branched; silica 

 in two rows of hooked spicules. 2. E. sylvaticum, 



var. pauciramosum 

 c. Stems practically alike, branched, excurrent, green ; silica in tiny transverse 

 ridges ; sheaths of the stem rather loose, with black scarious -margined teeth ; 

 branches strongly ascending, straight, subsimple. 3. E. palustre 

 b. Sheaths on the main stem with 15-20 firm dark persistent teeth, close ; stems 

 practically alike, green, reed-like, branched or simple ; central cavity 4/5 diam. 

 of stem; vallecular canals small or lacking; silica in tiny transverse ridges; 

 branches mostly near the middle of the stem, strongly ascending, subsimple, 

 of varying thickness. 4. E. limosum 



a. Stems perennial, all alike, stiff and harsh, normally unbranched or irregularly 

 branched near the base ; spikes apiculate. 

 b. Stems tall, reed-like, hollow, many -grooved, 3-7 mm. in diam. ; sheaths many- 

 toothed, the teeth soon deciduous. 5. E. hyemale, var. affine 

 b. Stems low, solid, very slender, 6-grooved, tufted and flexuous, about 0.5 mm. in 

 diam. ; sheaths mostly 3-toothed. 6. E. scirpoides 



1. E. arvense L. Common Horsetail. 



Moist or rather dry sandy or gravelly soils lacking in humus, also found frequently 

 in clay, in open places especially along embankments ; common. Apr.-May 15. 



Newf. to Alaska, southw. to N. C. and Calif., including the Atlantic Coastal Plain. 

 Found also in Eurasia. 



The forma dccumbcns (Meyer) Luers. (see Fern Bui. 7:86. 1899), with the 

 fertile stems bearing persistent green branches as on sterile stems, was found in the 

 bog at Lake Como (W. C. Muenscher & R. S. Nans). 



2. E. sylvaticum L., var. pauciramosum Milde. Wood Horsetail. 



Boggy meadow land and swampy woods, on gravelly, neutral, often alluvial, soils ; 

 frequent. May-June 10. 



Hilltop n. w. of North Spencer; near headwaters of Dry Run; s. w. of Key Hill; 

 Michigan Hollow Swamp; Warren woodlot, Fall Creek; Ellis Hollow, in alluvial 

 soil; Freeville Bog (D. in C. U. Herb.!) ; Mud Creek, Freeville; McLean Bogs. 



Newf. to Alaska, southw. to Va., Ohio, and Iowa, including the northern Atlantic 

 Coastal Plain. Found also in Eurasia. 



All the material seen from the Cayuga Lake Basin is forma midtiramosum Fernald 

 (Rhodora 20:131. 1918). 



3. E. palustre L. 



Marl bogs and springs ; rare. July. 

 Larch Meadow, 1922 (W. E. Manning !). 



Newf. to Alaska, southw. to Conn., N. Y., 111., and Wash. ; rare or absent on the 

 Atlantic Coastal Plain. Found also in Eurasia. 



4. E. limosum L. (See Rhodora 23:43. 1921. E. flnviatilc of Gray's Man., ed. 7.) 



Pipes. 



Swales and mud banks, in calcareous or neutral soils ; frequent. May 25-June. 



Inlet Marshes (D. in C. U. Herb.!) ; Cascadilla Creek, toward Ellis Hollow; Ren- 

 wick flats ; pond at Mecklenburg ; swale w. of Jacksonville ; e. of Montezuma ; on 

 the quaking moor of Vandemark Pond ; and elsewhere. 



