186 FLORA OF LOWER COAL MEASURES OF MISSOURL 



perhaps essentiall}" a sheatli, as shown frag'mentavily iu Fig. 1, PL L, which 

 represents a portion of No. 829G of the Lacoe collection, from Henry 

 County, identified by Professor Lesquereux. This character of the pairing, 

 which constitutes bifurcation of the leaves in effect, and which is also 

 illustrated in PI. L, Figs. 2 and 4, and in the enlarged details, accentuating 

 the Sphenophylloid nature of the plant, is further accompanied, in some 

 cases at least, by a corresponding bifurcation of the single basal nerve, one 

 of whose divisions passes to each lobe.-' From the preservation of the older 

 portions of the stems it would seem that these bifurcated (or paii-ed) leaves 

 gradually part and become distinct in the older stems, as Potoni^ has 

 noticed occasionally in tlie leaves of Equisetites zeceformis (Schloth.) A]\dra, 

 and that both forked and simple leaves may occur on the same stem. In 

 some cases there appear to be but three leaf pairs on the young twigs, but 

 this incomplete observation ma}^ be erroneous. The young twigs with 

 bifurcated leaves are frequently united with the larger stems, in which, so 

 far as I am able to discover, the leaves are separate quite to the base. 



Among several fertile spikes attached to the branches of this species I 

 have not yet seen any with the structure illustrated in the Coal Flora, 

 though the original of pi. iii, fig. 3, of that work lies before me. All the 

 specimens are too poorly preserved to enable me to discover the mode of 

 attachment or even the normal place of the sporangia between the verticils. 

 The bracts are more slender and xather longer than the leaves below, and 

 are iiiore strongly reflexed before curving outward, upward, and, finallv, 

 slightly inward. Tlie sporangia, a number of which are scattered irregularly 

 among the verticils in some of the specimens, are slightly oval and nearly 

 1 mm. in greater diameter. 



As a species of Aster opki/Uites this form is unique. In its' general 

 composition and make-up it is a Sphenophylluin. Its habit, the broadly ribbed 

 stems, the inflated joints, the verticils, which appear to be confluent with the 

 upper ends of the ribs, giving the leaves a decurrent effect, the bifurcated 

 character of the leaves, at least in the younger stages, all combine to make 

 us question whether we are not in reality dealing with a type more nearly 

 related to SphenophyUum, in which most of the nerves are simple to the base 

 of the leaf, so as to allow the lobes to grow apart with the enlargement of 



' In most cases, howevor, both the lenres and the nerves appear to be simple, especially iu the 

 lowi r portions of the stems or branches. 



