Lesquereux.] ^iJ\J [Feb, 18, 



been found attached to trunks of Sigillaria as roots. From this fact Stig- 

 maria plants have been generally admitted as true roots and are so in cer- 

 tain circumstances. 



On this subject Prof. Williamson says, that Stigmaria belongs alike to 

 Lepidodendron and to Sigillaria as root. I have never seen any positive 

 relation of these two genera of plants, or never found any remains of Stig- 

 maria in connection with those of Lepidodendron. Even in what 

 seems to be a creeping state, or rooting like that of some Lycopods, the small 

 intertexted stems of Lepidodendron exactly preserve the peculiar form of 

 their leaf-scars and never have round areoles like Stigmaria. 



What was known formerly of the structure of these plants by the ana- 

 tomical analysis of phytopaleontologists is confirmed by the researches of 

 Prof Renault. However, from the mode of life of the Stigmarics which 

 in certain cases and for long periods of time appear to have had an inde- 

 pendent vegetation, he supposes that these plants are of two kinds ; some 

 roots, others rhizomas. 



In transversal section of Stigmaria ficoides , he has observed as obliquely 

 traversing the woody cylinders two kinds of vascular fascicles, the first 

 numerous, reaching to the outside, true vascular bundles of leaves ; the 

 others less numerous in the interior of the wood, which represent fascicles 

 of roots. Hence in certain circumstances Stigmaria plants bear leaves ; 

 in others, fascicles of roots may be developed. 



I have already at different times exposed my views on the variable nature 

 of these plants according to their mode of vegetation. They have been 

 more recently resumed in the description of the genus Stigmaria, Coal 

 Flora of Pennsylvania and the United States, 1881, page 500, &c., and I 

 think that they agree in all essential points with the opinion of the French 

 author. Stigmarice as stems (or rhizomas) have lived independently and 

 for long periods of time floating at the surface of the swamps of the Car- 

 boniferous, or covering the soft mud, without producing any fructifications. 

 In this case the stems, horizontal, rarely branching (dichotomous), pre- 

 serve a uniform size, and bear also tubulous leaves only, more or less regu- 

 larly disposed in spiral, no rootlets. Wide surfaces of rocks are covered 

 with plants of this kind, and thick strata of clay are filled or composed of 

 their remains, without any fragments or traces of Sigillaria. This vegeta- 

 tion may be called adventive. But in another case the germinating process 

 may begin on sand or on a floating carpet of stems of Stigmaria, having 

 become compact and solid enough to support trees. Then the growth of 

 the plant from the production of a vertical bud proceeds upward and 

 downward, and the basilar appendages, first obliquely inclined down- 

 ward, become gradually more or less vertical as true roots and bear root- 

 lets, often still mixed with leaves, as seen by their scars of different size 

 and conformation. This kind of vegetation finds an analogy in that of a 

 number of floating plants of our time : Mosses, Lycopods, etc.* 



* Grand 'Eury has lately, in exploring the coal fields of Germany, recognized 

 these two distinct niodes of vegetation of the Stigmaria. 



