514 ISQETACE^. Isoetes. 



Order CXXX. ISOETACEtE. Bartl The Quillwort Tribe. 



Fructification adhering to the dilated bases of the leaves. Involucres membra- 

 naceous, not opening, one-celled : some of them containing large crustaceous 

 roundish grains ; others a fine powder ; both attached to numerous transverse 

 threads, which are arranged in rows, and divide the cavity of the involucre 

 into several vertical cells. — Submersed herbs, with a very short stem, which 

 throws down numerous fasciculate fibres. Leaves numerous, radical, subulate- 

 linear. Nearly related to Lycopodiace^e. 



1. ISOETES. Linn.; DC. organog. 2. p. 140. t. 56, 57. quiLLWORT. 



[From the Greek, isos, equal or similar, and elos, the year ; an evergreen.] 

 Character that of the Order.. 



1. Isoetes lacustris, Linn. Common Quillwort. 



Linn. sp. 2. p. 1100 ; Willd. sp. 5. p. 534 ; Pursh, fl. 2. p. 671 ; Nutt. gen. 2. p. 253 ; 

 Torr. compend. p. 390 ; Beck, hot. p. 462 ; Darlingt. Jl. Cest. p. 590. 



Roots long and fibrous. Stern very short and succulent. Leaves or fronds 2-10 inches 

 long, dilated and imbricate at the base. Involucres oval, membranaceous ; the posterior side 

 adnate to the dilated base of the leaf, and the upper part somewhat covered with a leafy scale, 

 which is broad and 2-lobed below, and acute above. The involucres of the exterior leaves 

 are filled with 50 - 80 spherical bodies, which are whitish when ripe. The integument is 

 crustaceous, muricate-reliculate externally, and polished within. At the base there are three 

 prominent radiating lines, which meet another line encircling the globule. The nucleus is 

 soft and oily. The involucres of the central leaves are divided into more numerous imperfect 

 cells, filled with exceedingly minute grains, which are whitish at first, but at length dark 

 colored ; these, when highly magnified, appear roundish oval and nearly smooth. 



Bottom of ponds and slow-flowing streams ; Oswego river, near the falls (Pursh). The 

 large granules of this plant have been observed by several botanists to separate at the 

 prominent circular and radiating lines, into 4 pieces; but I have never seen them do so. 



