134 
IOWA ACADEMY OF SCIENCES. 
Fagoinjrum esculentum, Moencli. 
Figure 14, plate, ix 
In this species “ palisade” cells appear different in the angles 
of the seeds than on sides. In the angles the ‘ ‘ palisade ” cells are 
much reduced, being nearly round, with a small, round cell-cavity, 
but in the angles of achenium, the ‘ 'palisade” cells become longer 
and the cell-cavity also elongates. The cell is light colored and 
cavity brown. In the “ sub-palisade ” portion five layers of 
cells are present. First — a large square layer occurs; immed- 
iately beneath this is a small chain- like layer of cells, and 
lastly occurs a layer resembling very much the first. The 
endosperm consists of long regular cells. Measurements — 
whole achenium I.65u, “palisade” cells 99u, “sub-palisade” 
cells 66u. 
CONCLUSIONS. 
In general the structure of the testa offer few" characters 
that are of sufficient importance to distinguish species, as the 
related species have similar structures. The genus Polygonum 
is easily distinguished from Burnex, by its papillate pro- 
jections which occur on the surface of the achenium. In Poly- 
gonella gracilis these papillate projections likewise occur. The 
small canals radiating from cell- cavity in palisade like cells of 
the genus Polygonum are too variable and not constant enough to 
be of service in the separation of species. However, studies of 
this kind are of service and value in botanical work simply as a 
knowledge of plants as a whole. 
DESCRIPTION OF PLATES. 
Figure 1. — Polygonum virginianum; a, palisade cells; b, sub-palisade 
cells; c, endosperm; b, embryo. (Plate vii.) 
Figure 2. — P. convolvulus; a, palisade cells; b, sub-palisade; c, endo- 
sperm. (Plate viii.) 
Figure 3. — Polygonum dumentorum,, a, palisade cells; b, sub-palisade; c, 
endosperm: b, embryo. (Plate vii.) 
Figure 4. — Polygonum Hydropiper; a, palisade cells; b, c, sub-palisade 
layers; d, endosperm; b, embryo. (Plate ix.) 
Figure 5. — P. erectum; a, palisade cells; b, sub-palisade; c, endosperm; 
b, embryo. (Plate vii.) 
Figure 6. — P. Persicana; a, palisade cells: b, sub-palisade layer; c, endo- 
sperm; b, embryo. (Plate viii.) 
Figure 7. — Erigonum; a, palisade cells; b, sub-palisade; c, endosperm. 
Figure 8. — Polygonella gracilis ; a, palisade cells; b, sub-palisade; c, enod- 
sperm: b, embryo. (Plate ix.) 
Figure 9. — Brunnichia cirrhosa; a, palisade cells; b, sub-palisade; c, 
endosperm; b, embryo. (Plate viii.) 
