rhoptometer (ῥοπτόν, something absorbed), an instrument to measure absorption of water by the soil.
rhyaci´um (ῥύαξ, ακος, mountain torrent), a torrent formation; rhyacad, a torrent plant.
rhysi´um (ῥυσίς, a flowing of fire), a succession due to volcanic action.
ruber, red.
saccospore (σάκκος, sack), a plant with sack-like disseminules.
sarcospore (σάρξ, σαρκός, flesh), a plant with fleshy disseminules.
sciad (σκιά, shade), a sciophyte; sciophyll, the leaf of a shade plant; sciophyte, a shade plant; sciophyti´um, a shade plant formation; sciophilous, shade-loving.
selagraph (σέλας, light), an instrument for recording light values automatically.
serotinal, late, pertaining to autumn.
social, used of plants in which the individuals are compactly grouped; exclusive, excluding individuals of other species; inclusive, permitting the entrance of individuals of other species.