GLOSSARY 321 
ponti’um (cvros, deep sea), a deep sea formation. 
potami’um (zorapds, river), a river formation; potamad, a river plant. 
potometer (zoroy, drink), an instrument for measuring absorption. 
prevernal, pertaining to early spring. 
prior, earlier, used of alpine aspects. 
prochosi’‘um (zpcxywors, a deposition of mud), a succession in an alluvial soil. 
prodophyti’um (poodos, pioneer), an initial formation, 
protodoche (zpéros, first), a primary succession. 
proximity ( proximitas, nearness), nearness to the area invaded. 
psamathi’um (dya6os, sand of the seashore), astrand formation; psamathad, 
a strand plant; psammozenous (ydupos, sand), producing a sandy soil. 
psilitum (Ad, land without trees), a prairie formation; psilad, a prairie 
plant. 
psychrometer (yvypos, chill), an instrument that measures humidity by means 
of a fall in temperature; psychrograph, a psychrometer that records 
automatically. 
ptenophyti’um (zryvés, passing), an intermediate formation. 
pterospore (arepcv, wing), a plant with winged disseminules. 
purpureus, purple. 
pycnophyti‘um (zv«vés, thick), a closed formation. 
pyri‘um (zip, fire), a burn succession. 
quadrat (guadratum, a square), a square meter of vegetation marked off for 
counting, mapping, etc.; major, a quadrat of 2-14 square meters. 
reaction, the effect of the formation upon the habitat. 
relict (velictus, left), a species belonging properly to an earlier type of succes- 
sion than the one in which it is found. 
repium (féro, sink), a succession due to subsidence. 
rhoi‘um (fos, stream), a creek formation; rhoad, a creek plant. 
rhoptometer (fo77év, something absorbed), an instrument to measure absorp- 
tion of water by the soil. 
rhyaci‘um (vag, axos, mountain torrent), a torrent formation; rhyacad, a 
torrent plant. 
rhysi‘um (vais, a flowing of fire), a succession due to volcanic action. 
ruber, red. 
saccospore (odkxos, sack), a plant with sack-like disseminules. 
sarcospore (odpé, capxés, flesh), a plant with fleshy disseminules. 
sciad (cxd, shade), a sciophyte; sciophyll, the leaf of a shade plant; scio- 
plyte, a shade plant; sciophyti‘um, a shade plant formation; sciophil- 
ous, shade-loving. , 
