136 Mr. J. Miers on Ephedra. 



With the Myricacece, Ephedra agrees in many points of struc- 

 ture, the most prominent of which are, its diclinous flowers in 

 amentiform spikelets; its bract-like involucels; its two-lobed 

 perigonium ; its monadelphous stamens ; its simple ovary, with 

 a single, erect, atropous ovule ; its one-celled fruit, with a soli- 

 tary erect seed ; and its embryo with a superior radicle. Myrica 

 differs, however, in its habit; its alternate leaves; its peri- 

 gonium in the form of two hypogynous scales, which remain and 

 become agglutinated to the fruit ; in its more distinct stamens, 

 with anthers bursting longitudinally ; in its two stigmata ; and 

 in the want of albumen in the seed. Although these points 

 show a considerable interval in the positions of these two fami- 

 lies, it is still evident that a notable degree of approximation 

 exists between the Gnetacece and Myricacece. 



The Gnetacece, in their jointed stems and floral structure, offer 

 many points of approach to the Chloranthacece, Piperacece, and 

 Saururacece ; but the absence or depauperation of floral envelopes 

 in those families, and the presence of a vitellus or embryoniferous 

 process which surmounts the albumen, of which we find no trace 

 either in Gnetum or Ephedra, are features which well characterize 

 the above families as a peculiar group, having little connexion 

 with the Gnetacece. 



Excepting their amentiform diclinous inflorescence, there is 

 nothing in the structure, of the Betulacece, Ciipaliferce, Arto- 

 carpece, and other consociate families, that offers any relation 

 with the Gnetacece. 



In its aphyllous habit, its geniculated nodes, and vaginant 

 bracts in lieu of leaves, Ephedra presents some similitude to 

 Calligonum, Pterococcus, and Calliphysa, with which it accords 

 also in its tubular petaloid perigonium, seated in the axils of a 

 general involucre — thus approaching the structure of the Erio- 

 gonece, and more particularly that of Chorizanthus vaginatus, 

 which has its stems furnished with opposite bracteiform leaflets 

 united into a membranaceous sheath, as in Ephedra. The Poly- 



cately membranaceous, darkish brown, without the trace of any embryo 

 within it. Upon the outer integument of the fertile seed, the white cord 

 continues to ascend from the point of its furcature, and terminates in the 

 apical micropyle, which is much darkened. There is no trace of any albu- 

 men within the integuments ; and the contained embryo, which is not half 

 their length, floats loosely in the upper part of the vacant space, generally 

 with the radicle pointing to the micropyle, or at other times lying obliquely 

 across the vacant space. The cotyledons are oval, flattened, and foliaceous, 

 with a superior terete radicle of about half their length. 



It will be seen that there is very little analogy in the whole of this sin- 

 gular structure to Ephedra ; and although the orthotropous embryo lies 

 atropously in regard to the hilum, it is amphitropous in respect to the 

 chalaza. 



