LIl] EPHEDRA 461 



tracheids. Attention is drawn to the resemblance of the outer 

 integument to the integument of Bennettites, and the single ovule 

 of Ephedra is considered to be the representative of the whole 

 ovulate strobilus of Bennettites of which it is a much reduced 

 derivative. There is a deep pollen-chamber at the apex of the 

 nucellus 1 and there are 2 8 long-necked archegonia at the summit 

 of the prothallus (endosperm). In its female prothallus and 

 sexual apparatus Ephedra differs considerably from Gnetum and 

 Welwitschia. The second envelope forms the hard shell of the 

 seed which is enclosed by bracts either in the form of membranous 

 wings (sect. Alatae) or as a red or yellow flesh (sect. Pseudobaccatae). 



Ewart 2 found that the seeds of Ephedra distachya germinated 

 after 93 days' immersion in sea- water. 



The male flowers 3 occur also in strobili on dichasial inflorescences, 

 a single flower occurs in the axil of each of the fertile bracts. A 

 flower consists of a short axis bearing a pair of membranous 

 appendages and the flower-axis is prolonged as a simple or bifid 

 stalk bearing bilocular synangia, 2 6 according to the species. 

 In some cases the central stalk or antherophore of the flower is 

 flattened and laminar 4 instead of the usual cylindrical form: it 

 has been interpreted both as an axial and a foliar structure, but 

 the latter interpretation is probably correct. Arber and Parkin 5 

 regard the antherophore as having been formed from two fused 

 members, and this view is adopted by Mrs Thoday and Miss 

 Berridge. On the basis of this interpretation the microsporophylls 

 of E-phedra, represented by the antherophore, are considered to be 

 homologous with the disc of sporophylls of a Benettitean flower 

 and with the stamens in a male flower of Welwitschia. Anatomi- 

 cally 6 Ephedra exhibits a closer agreement with the Conifers and 

 in some respects with the Dicotyledons than with recent Cycads 

 or the Bennettitales. The presence of vessels in the secondary 

 xylem is an Angiospermous feature though in structure they differ 

 from the Angiospermous type; the pitting of the tracheids is in 

 the main Abietineous but the occurrence of compressed pits 



1 Land (04); for other references, see Lignier and Tison (12); also Sigrianski (13) 

 - Ewart (08). 



3 Thibout (96) gives a good account of the male flowers of the Gnetales. 



4 Thoday and Berridge (12) p. 970. 5 Arber and Parkin (08). 

 6 Thompson (12 2 ). See also Jeffrey (17) p. 357. 



