9 8 
The Ohio Naturalist. 
[Vol. VII, No. 5, 
Sagittaria variabilis. 
1. Monoecious or sometimes 
dioecious. 
2. Leaves sagittate, variable in 
form and size, sometimes 
broader than long, 15-40 
cm. long, basal lobes, ovate 
or lanceolate, acute or 
acuminate. 
3 Scapes 3- 6 dm. long, angled, 
simple or branched. 
4. Filaments not dilated, gla¬ 
brous. 
5. Mature heads 1.5-3 cm. in 
diameter. 
6. Bracts 1.5 cm. long, gla¬ 
brous, acute or acuminate. 
7. Flowers 1.5-2.5 cm. broad. 
8. Achenes obovate, about 2-4 
mm. long, erect, undulate 
winged; beak ascending or 1 
recurved. 
9. Summer and fall. 
Sagittaria lancifolia. 
1. Monoecious. 
2. Leaves not variable, 4-9 
dm. long; leathery, broadly 
linear or elliptic, acute. 
3. Scapes 6-20 dm. long, sim¬ 
ple or branched. 
4. Filaments not dilated, pu¬ 
bescent. 
5. Mature heads 1 cm. in diam¬ 
eter. 
6. Bracts ovate or ovate-lan¬ 
ceolate, 1-2.5 cm. long, 
acute or acuminate. 
7. Flowers 1-2.5 cm. broad. 
8. Achenes cuneate or obo¬ 
vate, 2-3 mm. long, winged; 
beak short, ascending. 
9. Spring and summer. 
With such striking external differences one would naturally 
expect equally interesting internal differences but to my surprise 
I found the development of the embryo-sac and embryo of 
S. lancifolia practically the same as had been described by 
Schaffner for 5. variabilis. The comparison with Schaffner’s 
results will be brought out in the following discussion. 
Embryo-sac. 
The author was unable to determine the origin and develop¬ 
ment of the archesporium satisfactorily but traced without 
difficulty, the deveropment of the embryo-sac beginning with the 
one-nucleate stage (Fig. I). In the formation of the two- 
nucleate (Fig. 2) stage the sac elongates to twice the length of 
the one-nucleate stage. Schaffner did not secure material for 
these two stages but from this point on the development of the 
embryo-sac of the two species is exactly the same, except that I 
was inclined to believe the antipodals in 5. lanceolata not quite 
so presistent as he found them in S. variabilis. 
Endosperm. 
The development of the endosperm follows exactly the same 
course as that of 5. variabilis as described by Schaffner. Schaffner 
did not fully understand the significance of the lower endosperm 
