Pubescent. Covered with short soft or downy hairs.
Raceme. A simple cluster of pediceled flowers upon a common axis.
Rachis. The main axis of a compound leaf, of a raceme or of a spike.
Ramification. Branching.
Range. The geographical extent and limits of a species.
Reflexed. Turned backward.
Reticulated. Netted; in the form of a network.
Revolute. Rolled backward from the margin or apex.
Samara. Key fruit; winged fruit, like that of the ash or maple.
Scarf-bark. The thin, outermost layer which often peels off.