140 BOTANICAL GAZETTE [FEBRUARY 
on the Essex plain averages 6 trees on 25°1™. Vaccinium pennsyl- 
vanicum forms a carpet beneath, and growing up through this, one 
finds on the average square meter 13 Pteris, 5 Gaylussacia baccata, 
14 Melampyrum lineare, 8 Carex pennsylvanica, 1 Rubus alleghe- 
niensis, t A pocynum androsaemifolium. 
0 ii] 0 PO D 
Md F 0 
ulD F D 
R poole bee 
0 Bee ane 
77 7] F] D — <a eens 
(3 Bal le Ga 
Bal oy-]o blo mee Ss % 
a ao 
eS a oe 
R 0 L) pi pp Pp 
Hee 0} R JR aRREE Re 
Po 
D F 0 Ene ae 
7D Lenk Beaes 
R L 0 | {OF Pp 
F PC Of ff 
i ie 
kd RiR Yes, Ge Be el St 
of0 0 por 
CLES foto 68 Bea) sO 
b) D BEBE DSkes 
0 Ree! 
PR BewBREE Ss 
Hy olo PC 0 Oo} ft tt pt 
ier fd Ue a A Se FR ae Oe Shs ee ae 
0 oy [Rr 0 = 0 Pip Pp 
F aon mee on ae 
8 eC PERE MERE 
0 A ye ie 
ppp 0 ag 
0 R Pt tt 
FHResU GUase 
d Ce 
Q D PRS SERakss-. 
) ojo cee see 
a fret PT ttt 
| {8 PC D Pt 
= 0 kok nese 
bot peer JURSR ae S 
- Ag o 0 22 
od Be Be Be Be 3 ie Reese 
; BREE Res 
Rg [ BESe- 
3 0 | | 0 & 0 aaene 
l | aes 
itch 
i=) 
Fic, 8.—Sample plot 25. Danthonia-Polytrichum pasture being invaded by 
pine; open patches occupied by Polytrichum; Colchester plain, 1 square meter 
D, Danthonia spicata 89; R, Rumex Acetosella 13; F, Fragaria virginiana 10; PC, 
Panicum capillare 6; PR, Pinus rigida 2. 
we 
By the time pitch pine which has taken possession of the abandoned 
fields in the manner described above is 60 years old, the stand has - 
become much less dense, averaging only one tree on 25°". The 
ground beneath is: much less shaded and the soil is richer from the 
accumulation of humus. At this point white pine quite commonly 
