TYPHACE^, NAIADACE^. 145 



1. Ty'pha. Flowers in a very dense and long cylindrical terminal spike, the 



upper ones staininate, the lower pistillate, the ovaries long-stalked and 

 surrounded by copious bristles forming the down of the fruit. Leaves 

 sword-shaped, erect, sheathing the stein below. 



2. Sparga'nium. Flowers in separate globular heads along the upper part 



of the stem, the higher ones staminate, the lower pistillate, each ovary 

 sessile and surrounded by a few scales not unlike a calyx. Both kinds 

 of heads leafy-bracted. Leaves flat or triangular, sheathing the stem 

 with their bases. 



1. TY'PHA, Tourn. CAT-TAIL FLAG. 



1. T. latifo'lia, L. (COMMON CAT-TAIL.)' Stem 5-8 feet high. 

 Leaves fiat. No space between the staminate and pistillate parts 

 of the spike. Marshy places. 



2. T. angustifo'lia, L. (NARROW-LEAVED of SMALL CAT- 

 TAIL.) Leaves channelled toward the base, narrowly linear. The 

 two parts of the spike usually with an interval between them. 

 Central and eastern Ontario. 



a. SPARGA'NIUM, Tourn. BUR-REED. 



1. S. eurycar'pum, Engelm. Stem erect, stout, 2-1 feet high. 

 Leaves mostly flat on the upper side, keeled and hollow-sided on 

 the lower. Heads several, panicled-spiked, the pistillate an inch 

 across in fruit. Nutlets or achenes with a broad abruptly- 

 pointed top. Borders of slow waters and ponds. 



2. S. Simplex, Hudson, var. angUStifo'lium, Gray. (-9. affine, 

 Schnitzlein, in Macoun's Catalogue.) Stem slender, erect, 1-2 

 feet high ; the leaves usually floating, long and narrowly linear. 

 Heads several, usually in a simple row, the pistillate supra- 

 axillary, about half an inch across. Nutlets pointed at both ends. 



Var. Nuttallii, Engel., (S. simplex, Hudson, in Macoun's 

 Catalogue,) has the lower pistillate, heads axillary, and the 

 fruiting heads perhaps a little larger. In slow streams. 



ORDER XCIII. NAIADA'CEJE. (PONDWEED FAMILY.) 



Immersed aquatic herbs, with jointed stems and sheathing 

 stipules. Leaves immersed or floating. Flowers (in our common 

 genus) perfect, in spikes or clusters, with 4 sepals, 4 stamens, and 

 4 ovaries ; the spikes generally raised on peduncles to the top of 



