Evolution of Plants 363 



stomata as set forth by Porsch {123: 41) forms a highly impor- 

 tant similarity; the reduced, whorled, scale-like leaves are 

 also suggestive. But it is in the flowers and fruit that even 

 nearer affinities are shown. 



In both, the flowers are diclinous often dioecious, and of 

 condensed but simple type. In both they are arranged in 

 sessile decussate or whorled manner, though Gnetum gnemon 

 in this respect more closely suggests Casiiarina than does 

 Ephedra. In both, the staminate flowers are surrounded by 

 4-2 decussate perianth scales; in both, a single staminate 

 pillar ends in an antherine mass, that in Ephedra bears 8-2 

 anthers, in Casiiarina 2 only; in both, the anthers are bilocular 

 and contain oval pollen grains. The pistillate flowers in both 

 form condensed oval spikes, and each flower has been con- 

 sidered to be devoid of a perianth. Each flower however 

 consists of parts that have excited much discussion. The 

 WTiter believes that for these an exact homology can be estab- 

 lished between them. 



In Ephedra helvetica the careful studies of Jaccard fortify 

 the somewhat diverse and yet related views of Van Tieghem 

 and Strasburger, that each flower is surrounded by a pair of 

 fused leaves. These we would regard with Jaccard as a rudi- 

 mentary perianth. In Casiiarina siiberosa, according to Treub, 

 two leaves also arise right and left of the developing pistil, 

 which we would also interpret as corresponding to the perianth 

 of Ephedra. But in Ephedra trifurca according to Land four 

 perianth leaves are formed; and tliis again is duplicated in 

 Casuarina equisetifolia, wliich bears a like number. 



In Ephedra trifurca. Land has shown that the so-called integ- 

 umen arises as two swellings wliich elongate greatly after 

 fusing. This has usually been regarded as an ovular or mega- 

 sporangial integument, but the writer would regard these as 

 two carpels which early fuse and elongate to form a long open 

 stylar canal. Such then presents a close approximation to an 

 angiospermic state. In Casuarina Treub's embr^^ological 

 studies show similarly that two carpellary swellings are formed 

 which early fuse and rapidly elongate to form the long style. 



