pyxis. A dry fruit or capsule in which the top comes off, like a cover to a jar.
raceme. A simple (unbranched) cluster in which the flowers are on short pedicels and open from the base upwards.
raphe. A ridge or elevation on some seeds caused by the seed-stalk and seed-coats growing together.
ray. The elongated corolla-limb of some members of the Compositæ family.
receptive. Said of a stigma when it is “ripe” or ready to receive the pollen.
regular flowers are those in which all the members of each series (as all the sepals, or all the petals, or all the stamens) are like each other in shape, size, and colour.
reinforced. See [accessory fruits].
respiration. Breathing; manifest by oxygen taken in and carbon dioxide given off.
rhizome. A rootstock; an underground root-like stem. It has joints, usually scales representing leaves, and is often thick and fleshy.
samara. A key fruit, being an indehiscent (not opening) fruit provided with a wing or wings.