Well established in spring-fed back-waters of the San Marcos River in Hays 

 Co., Tex. where it was originally introd. (probably about 1960); nat. apparently 

 to both hemispheres; also in s. Fla. 



It is quite possible that the other two species in this genus, C. pteridoides 

 (Hook.) Hieron. and C deltoidea Benedict, may be introduced in Texas rivers. 

 In contrast to C. thalictroides, they both have broadly deltoid fronds. The sterile 

 fronds of C. pteridoides are usually simple with broad basal lobes and short, often 

 swollen, stipes that are widest at base of blade and tapered downward, while the 

 sterile fronds of C. deltoidea are pinnately divided, with long, slender stipes. 



Division II. Spermatophyta 



Seed-Bearing or Flowering Plants 



Plants producing seeds that contain the young plants in a dormant condition 

 until germination. Sporophylls arranged in groups (flowers) of definite or in- 

 definite numbers, heterosporous, those bearing microsporangia (anther sacs) 

 termed stamens, those producing macrosporangia (ovules) carpels. The game- 

 tophytes very much reduced, the female being confined within the macrosporangia 

 where its egg-cell is fertilized by the spermatozoid of the male gametophyte (pollen 

 tube), the sporophyte thus beginning its development while still attached to the 

 sporophyte of the preceding generation. Eventually detached in an embryonic 

 stage, together with the enclosing tissues, as a seed. 



The seed-bearing plants form the most numerous plant group in existence, more 

 than 200,000 species being known. The seed-habit, now restricted to the Spermato- 

 phyta, is also known to have occurred in ancient fernlike plants. This category 

 is now considered essentially one of convenience rather than distinction because 

 of the apparent diverse ancestry of its component members. 



Class 1. Gymnospermae 



Plants monoecious or dioecious, more or less resinous trees or shrubs; ovules 

 and seeds not enclosed in an ovary, typically borne on scales that are arranged 

 in a cone or strobilus, or sometimes terminal on naked or bracteate stalks, micro- 

 sporangia mostly embedded in microphylls that are arranged in a cone or strobilus; 

 male and female cones distinct, dissimilar. 



The Gymnosperms comprise an ancient remnant of about 700 species of trees 

 and shrubs that are considered to have been most abundant in the Mesozoic. The 

 group contains such relicts as the Cycads, the Ginkgo tree, Metasequoia and 

 Araucarias. 



Fam. 12. Taxodiaceae Warming Taxodium Family 



Deciduous or essentially evergreen trees with light-brown furrowed and scaly 

 bark and upright or spreading branches; branchlets of two kinds, those near the 



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