Mr. J. Miers on Ephedra. 137 



gonace<2 generally, indeed, agree with the Gnetacea in their often 

 polygamo-moncecious or dioecious flowers, in their calycinoid in- 

 volucres; their petaloid perigonium; their stamens often mona- 

 delphous at the base; their usually one-celled ovary, with a 

 single erect ovule, which (as I have shown) becomes fertilized, in 

 the same manner as in the Gnetacece, by the direct influence of 

 the pollen through an aperture in the apex of the cell, without 

 the intervention of a placenta ; and, finally, in their indehiscent 

 one-celled fruit, bearing a single erect albuminous seed, covered 

 by two regular integuments, and enclosing an embryo with a 

 superior radicle. However remarkable these analogies may be, 

 which are in many respects shared with the NyctaginacecBy it is 

 impossible to place the Gnetacea in a position near these families 

 and their allies ; for the Oleracece of Endlicher form a most di- 

 stinct and natural group, well characterized by the peculiar fea- 

 ture of a curved embryo placed outside of a farinaceous albumen. 

 Although the relationship of the Gnetacece with the Urticacece 

 may not at first sight be apparent, still in many very essential 

 points an analogy exists, which is well deserving of attention. 

 The flowers in Urticacece are often diclinous, and in bracteated 

 spikelets. It has been shown {ante, vol. ix. 430) that their soli- 

 tary carpel, sometimes wanting a style, with sessile stigmata, 

 has a pervious opening in the apex of its cell, through which the 

 solitary erect ovule is directly fecundated by the pollen, without 

 the intervention of any placenta. This erect ovule is always 

 atropous, with two distinct integuments ; and its embryo, with a 

 small superior radicle, is enclosed in fleshy albumen. In these 

 remarkable particulars I know of no other order that so nearly 

 approaches the Gnetacece. On the other hand, the Urticacece are 

 very difierent in habit — in their usually (but not always) alter- 

 nate leaves, in the form of their inflorescence, and in the struc- 

 ture of the male flowers ; in the latter respect, however, a degree of 

 analogy remains, for it generally happens in these, as in Ephedra, 

 that the lobes of the perigonium are opposite to those of the 

 involucels. We find also in the inner bark of Ephedra, strong 

 fibres almost as abundantly as in the Urticacece : another similar 

 development invariably occurs in that genus, in the vaginant 

 stipulary leaves that surround each branchlet, at the point of its 

 origin in the axils. There is some approach in the floral struc- 

 ture of the Gnetacece to that of the Urticacece ; that is to say, it 

 is in both cases diclinous, the male flower in both families pre- 

 senting a gamophyllous perigonium seated generally in its own 

 involucel, or occasionally several perigonia within involucels 

 more or less confluent with each other. It is true that in Urti- 

 cacece the perigonium is often 4- or 5 -partite, but it is sometimes 

 2- or 3-fid, with equal segments ; the insertion of the stamens is 



