INFLORESCENCE
Inflorescence is a term commonly applied to the mode of flowering—i.e. to the arrangement of blossoms on the stem and their relative positions to one another.
A peduncle is the stem of a solitary flower, or the main stem of a flower-cluster;
a scape is a peduncle growing from the ground;
a pedicel is the stem of each flower in a cluster;
a bract is a small floral leaf;
an involucre is a collection of bracts around a flower-cluster or around a single flower.
Flowers may be solitary or clustered.
Solitary flowers or flower-clusters are—
terminal, when borne at the summit of the stem;
axillary, when borne in the axils of the leaves.
A flower-cluster is called—
a raceme, when the flowers are arranged along the axis upon pedicels nearly equal in length;
a corymb, when the flowers are arranged as in the raceme, with the lower pedicels elongated, making the cluster flat-topped;
an umbel, when the pedicels arise from the same point, like the rays of an umbrella, and the cluster is flat-topped;
a panicle, when compound, irregularly made up of a number of racemes;
a spike, when like a raceme, the flowers being without pedicels;
a spadix, when it is a fleshy spike, generally enveloped by a large bract, called a spathe, as in the calla-lily;
an ament, or catkin, when it is a pendent spike, with scaly bracts, like the Willow;
a head, when it is a shortened spike, with a globular form;
a cyme, when it is branched and flat-topped, usually compound, with the older flowers in the center of each simple cluster.