14 Bulletin of the University of Texas 



shoots in the axils of leaves, or at the end of the main axis of the 

 shoot. Flowers which occur in clusters may be grouped for 

 convenience into a number of definite types. A raceme of flowers 

 or fruits is an arrangement of the individual flowers on the 

 more or less elongated axis, each with a separate pedicel, all 

 about equal in length. A panicle is a flower cluster in which 

 the simple pedicels of the raceme become branched and spreading. 

 A corymb is also like the raceme, but in this case the flower shoot 

 is shortened, and the lower pedicels are longer than those borne 

 above them, so that the clusters become flat topped with all the 

 flow T ers borne at about the same level. A cyme resembles a corymb, 

 but in this case the pedicels become branched and the central 

 flower blooms first. An umbel is a flower cluster in which the 

 pedicels of the flowers start from the same point and become about 

 of equal length. A head is a cluster in which the axis is very 

 short and the flowers are without pedicels, or nearly so, forming 

 a globose or compressed cluster. A catkin, or ament. is a long, 

 slender, drooping axis which bears numerous solitary sessil 

 flowers in the axils of bracts, the whole cluster falling away after 

 the maturity of the flowers. Among trees, the willows, poplars, 

 oaks, and birches bear their flowers in catkins. 



A flower has been defined as the forerunner of a seed; but 

 plants bear their seeds in some kind of a structure known as a 

 fruit, consisting of the ripened ovary, and sometimes other ac- 

 cessory parts. The fruit is a structure which aids in the distri- 

 bution of seeds-. Fruits are either dry or fleshy. Dry fruits may 

 be grouped under two heads: those which open and shed their 

 seeds at maturity are dehiscent, those which do not open are inde- 

 hiscent. Of the indehiscent fruits, our commonest examples 

 among the trees are the samara or the dry winged fruits of 

 maples, elms, ash, ailanthus, hop tree, etc. ; the acorn of the oaks ; 

 the nut of the walnut and hickory. The dry dehiscent fruits are 

 known as pods if the seeds are fastened along one side and there 

 is but a single cavity, otherwise they are called capsules. 



Among the fleshy fruits our commonest examples are the berry, 

 pome, and drupe. The term berry may be used to denote all 

 fleshy fruits with more than one seed buried in the mass of pulp. 

 The pome or apple fruit differs from the berry by bearing the 

 seeds inclosed by a hardened substance. The drupe is a single- 

 seeded fleshy fruit. 



