SPHENOPSIDA 99 



A number of cones, referred to the genera Sphenophyllo- 

 stachys or Bowmanites, have been found attached to the 

 parent plant; others, found detached, are placed in these 

 genera on the basis of their general similarity. A number of 

 other genera of cones are also referred to the Sphenophy Hales, 

 but on less secure grounds. Some of them represent the most 

 complex cones in the whole plant kingdom. One of the 

 earUest to appear in the fossil record is Eviostachya, des- 

 cribed by Leclercq^*, from the Upper Devonian of Belgium. 

 Less than 6 cm long and less than i cm in diameter, each cone 

 had at its base a whorl of six bracts. Above this were whorls 

 of sporangiophores, six in each whorl. Each sporangiophore 

 was itself highly compUcated (Fig. 1 5G) and branched in a very 

 characteristic way (Fig. 15H), bearing a total of twenty-seven 

 sporangia in a reflexed position. Sporangiophores in successive 

 whorls stood vertically above each other, as is characteristic of 

 the Sphenophyllales, but there were no bracts between them. 



Cheirostrobus, from the Lower Carboniferous of Scotland, 

 was a large cone, 3-5 cm across, and had thirty-six sporangi- 

 phores in each whorl, subtended by the same number of 

 bracts, each with bifurcated tips (Fig. 15I). The arrangement 

 of the vascular supply to these appendages is interesting in 

 that a common 'trunk-bundle' supplied three sporangio- 

 phores and the three bracts subtending them. This has led 

 some morphologists to suggest a more comphcated inter- 

 pretation of the cone structure than is really necessary, based 

 on the supposition that each trunk-bundle represented the 

 vascular supply to one compound organ made up of three 

 fertile leaflets and three sterile leaflets. 



Sphenophyllostachys fertilis { = Sphenophyllum fertile, 

 = Bowmanites fertilis) from the Upper Carboniferous (Fig. 

 15J) was also a complex cone. Up to 6 cm long and 2-5 cm 

 in diameter, it was made up of whorls of superimposed 

 sporangiophores, six in a whorl, each subtended by a pair 

 of sterile appendages (possibly homologous with one bifid 

 bract). Each sporangiophore terminated in a *mop' of 



