174 Podostemacece. 



as the one we have just traced, as a glance at their compara- 

 tive structure will show. In Lacistemacea, the flowers are 

 arranged in catkin-like spikes, each flower being subtended 

 by a large bract. In the higher forms of Podostemacece, we 

 find a somewhat similar disposition of the flowers, each of 

 which emerges from the representative of the bract, a 

 spathe. In both a calyx exists, and neither possess a corol- 

 la. In both the stamens are hypogynous, and unilateral, 

 but not always so in Podostemacece ; and in both the fruit is 

 a 2 or 3- celled capsule. At this point, however, the re- 

 semblance ceases, for Lacistemacece has parietal placentas, 

 definite, albuminous seeds, and an inverted embryo, while in 

 Podostemacece, the placentas are attached to the dissepiments, 

 the seeds are numerous and exalbuminous, and the embryo 

 has the radical directed towards the hilum. 



I can trace but little resemblance between Podostemacece 

 and Piperacece, and still less between the former order and 

 Pistiacece ; notwithstanding that both Martius and Griffith 

 insist on the close connection which exists between them.* 



* Since the above was written, and while these sheets are with me for cor- 

 rection, I have received the new edition of Lindley's " Introduction to the 

 Natural System," which now bears the name of " The Vegetable Kingdom." 

 From the great mass of new matter which has been added to this edition, the great 

 alteration which has been made in the arrangement, and from every order having 

 one or more illustrations, beautifully executed, the work may almost be pro- 

 nounced to be a new one ; while from the value of the structural and systematical 

 disquisitions which head the superior divisions of his mode of classification, it is 

 not too much to say, that it is by far the most important contribution which has 

 been offered to the literature of Botany since the publication of the now world- 

 renowned "Genera Plantarum" of Jussieu. 



In " The Vegetable Kingdom," I find that the Podostemons are arranged along 

 with Elatinaceca at the end of the Kutal allianae, with the following observa- 

 tions:— " Although Podostemads must be considered to present a very strongly 

 marked approach to flowerless plants in some respects, yet we must look for some 

 more immediate relation. This I formerly thought might be found with Peppers 

 or Callitriche ; Meisuer suggests Hornworts (Ceratophyllacece), But if we re- 

 gard hermaphrodite flowers, hypogynous stamens, and an exalbuminous embryo 

 as the most important features in these plants, our views of its affinity will take a 

 very different direction, and we can scarcely fail to suspect an approach to water- 



