. Foundations of Botany. Botany. 188 FOUNDATIONS OF BOTANY spring from about the same point. This produces a flower-cluster called the umbel (Fig. 130). 199. Sessile Flowers and Flower-Clusters. — Often the pedicels are wanting, or the flowers are sessile, and then a modification of the raceme is produced which is called a spike, like that of the plantain (Fig. 132). The willow, alder, birch, poplar, and many other common trees bear a short, flexible, rather scaly spike (Fig. 131), which is called a catkin. The peduncle of a spike is often so much short- ened as to bring the flowers into a som
. Foundations of Botany. Botany. 188 FOUNDATIONS OF BOTANY spring from about the same point. This produces a flower-cluster called the umbel (Fig. 130). 199. Sessile Flowers and Flower-Clusters. — Often the pedicels are wanting, or the flowers are sessile, and then a modification of the raceme is produced which is called a spike, like that of the plantain (Fig. 132). The willow, alder, birch, poplar, and many other common trees bear a short, flexible, rather scaly spike (Fig. 131), which is called a catkin. The peduncle of a spike is often so much short- ened as to bring the flowers into a somewhat globu- lar mass. This is called a head (Fig. 132). Around the base of the head usually occurs a circle of bracts known as the involucre. The same name is given to a set of bracts which often surround the bases of the pedicels in an umbel. 200. The Composite Head. — The plants of one large group, of which the dandelion, the daisy, the thistle, and the sun- members, bear their flowers in on a common receptacle. The whole cluster looks so much like a single flower that it is usually taken for one by non-botanical people. In many of the largest and most showy heads, like that of the sunflower and the daisy, there are two kinds of flowers, the ray-flowers, around the margin, and the tubular disk- flowers of the interior of the head (Fig. 133). The early botanists supposed the whole flower-cluster to be a single 1. Fig. 132. — Spike of Plantain and Head of Red Clover. flower are well-known close involucrate heads. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bergen, Joseph Y. (Joseph Young), 1851-1917. Boston, Ginn & company
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