I70 REPORT OF NEW JERSEY STATE MUSEUM. 



It grows abundantly along- the shores of rivers and lakes or 

 fills entirely smaller ditches and ponds, sometimes on mud or in 

 swamps, entirely exposed above the roots, and at other times 

 submerged half-way to the blades and flowers. 



Well distinguished from the following si>ecies by its hori- 

 zontal achene beaks and its short bracts, it is extremely variable 

 in size and in the character of its foliage. So far as I am aware 

 the form with pubescent leaves, perhaps a distinct species, does 

 not occur within our limits, but our glabrous plants show ap- 

 parently all possible variation in hastate leaf forms. 



What is apparently the most widely prevalent form has a 

 broad blunt blade no mm. long from the petiole and about the 

 same width at the middle, while the lobes are lOO mm. long and 

 50 mm. wide at their middle, and more or less incurved or 

 parallel to the petiole. Petioles about 7.5 cm. (30 in.) long. 



Another style has the blade longer and acute, 180 x 85 mm., 

 lobes acute incurved 175 x 50 mm. 



A much smaller type of plant has petioles only 2 dm. (8 in.) 

 long, blade blunt and narrow with sides nearly parallel for most 

 of the length, 65 x 12 mm.; lobes still narrower, 60 x 6 mm. 

 This resembles the narrovz-leafed form of the next species so 

 abundant in the Pine Barrens, and like it, occasionally presents 

 leaves without basal lobes. In one instance I have seen such 

 leaves on the larger plant described above, the blades measuring 

 150 x 30 mm. Mr. Stewardson Brown tells me that a similar 

 plant which he placed in a garden pond later developed regular 

 sagittate leaves. 



Another form of the common Arrowhead with narrow leaves 

 has basal lobes strongly divaricate branching from the line of 

 the blade at an angle of 45°. Some of these are large, blade 275 

 X 25 rnm., and lobes 225 x 18 mm., while others measure only 

 225 X 12 mm., lobes 200 x 9 mm. The majority of the slender- 

 leaved plants are probably of this type. While each plant ap- 

 pears to produce leaves of but one type, except for the occasional 

 ones which lack basal lobes, I cannot see sufficient constancy of 

 form to warrant the use of varietal names. 



Fl. — Late July to late September. Fr. — Fully mature rarely 

 before September. 



