THE PLANT BODY 17 



toward the lateral branch. The form and anatomy of some solitary 

 prophylls suggest that the solitary organ represents two fused prophylls. 

 The solitary prophyll may have two apices and is frequently bvo- 

 keeled. Two to seven vascular bundles are present. Where there are 

 two bundles, one lies in each keel and one is larger than the other; there 

 is no median bundle. The older interpretation of this asymmetry is that 

 compression of the organ in ontogeny has distorted it, so that the mid- 

 dle part has become lateral. Form, position, and structure support the 

 view that the solitary prophyll clearly represents a fused pair; the 

 asymmetry results from closeness to the mother branch and con- 

 sequent difference in development. Location and number of buds axillant 

 to the prophylls should be further evidence of number of organs 

 present, but it is claimed that in the prophylls of some monocotyledons 

 there is only one bud. This is perhaps the condition to be expected if 

 prophylls are the reduced first leaves of a shoot; the distal node is nor- 

 mally the better developed and the only one to have an axillary bud. 

 Anatomy demonstrates that the prophylls are not stipules of the sub- 

 tending leaf; their vascular supply is derived from the lateral branch, 

 not from the mother stem. 



Prophylls seem to have no significance as unique appendages in the 

 shoot; they are merely leaves of reduced form, sometimes in apparently 

 peculiar positions. They seem to represent the first appendages of a 

 lateral shoot, weakly developed and sometimes displaced by closeness 

 to the mother shoot. The prophyll of monocotyledons is undoubtedly a 

 pair of leaves. 



The terminal leaf has been described as present in some reduced and 

 highly specialized shoots, as in some grass inflorescences. In these shoots, 

 the apical meristem has been transformed into a leaf primordium, and 

 the leaf is, ontogenetically, strictly terminal. Stages in the assumption 

 of a pseudoterminal leaf position in determinate shoots are seen in both 

 dicotyledons and monocotyledons. In sympodial growth of woody twigs, 

 the stem apex aborts and the dead tip may be abscised, as is a leaf, 

 either in a terminal position or after crowding to one side into an 

 apparently lateral position (Tilia, Cladrastis). In the monocotyledons, 

 evidence of the true position of an apparently terminal leaf may be 

 obscure or lacking. The genera Streptopus, Disporum, PolygorMtum, and 

 Uvularia show various stages in the loss of the stem tip. A vestigial apex 

 may be enclosed in the sheath of the distal leaf. In Uvularia, one 

 species shows no trace of a stem tip; another, a vestigial cone; another, 

 an obvious stem tip. The "terminal" position of leaves in herbaceous 

 monocotyledons is obviously secondary; the shoot apex is abortive or 

 lost, and a leaf assumes its position. Determinate leaves have somewhat 

 different origins in monocotyledons and dicotyledons. Similarly, a soli- 



