42 THE AMERICAN BOTANIST. 



The Anther filaments in the beard-tongue {Pets{emon) take 

 up the work and in the marsh marigold {Caltha palsfris) 

 the pistils are drawn into serv'ice. In the majority of plants, 

 however, it is the receptacle that is the nectar-producer and 

 this often produces special glands or disks in which the nectar 

 is found. 



Root-Climbers. — Plants have various ways of getting 

 up in the world. The morning-glory and hop find it expedient 

 to twine, the grape and Boston ivy develop tendrils that are 

 regarded as transformed branches, while the pea climbs by the 

 rachis of its leaf. Gloriosa superha climbs by the leaf tip, 

 clematis and nasturtium climb by their petioles, and the green- 

 briar (Sniilax), by stipules. This does not exhaust the kinds 

 of climbers. There are still the root-climbers, such as the 

 poison ivy and trumpet creeper (Bignonia) that produce aerial 

 rootlets which firmly attach them to their supports. It is be- 

 lieved by many that the contact of the vine with its support is 

 quite sufficient to cause these roots to develop and in general 

 this seems true, but anyone who has seen an old stem of poison 

 ivy must have noticed that the rootlets have certainly not all 

 arisen in response to this stimulus for they spring from all 

 parts of the stem. 



Origin of Petals. — Relying upon the resemblance be- 

 tween leaf-buds and flower-buds, botanists have often asserted 

 that the floral organs have been derived from leaves. While 

 it is doubtless true that "a flower is a transformed branch," the 

 exact order in which these parts have been transformed or, 

 rather, the order in which each part appeared is often mis- 

 understood or lost sight of. It is very certain that there were 

 pistils and stamens long before there were flowers in any 

 common usage of this term. Pollen grains and certain struc- 

 tures in the ovules of plants are simply spores comparable in 

 all respects to the spores that appear in the spore-cases on the 



