Morphology of the Female Floiver of Gnetum. 
79: 
knowledge, greater than if it can be shown to be foliar. This very fact 
justifies a demand for clear proof that it is other than it seems. 
Most investigators have accepted the facts on their face value and have 
concluded, or have seen no reason to question the conclusion, that the flower 
is a bud and that the ovule terminates the floral axis.* 
Van Tieghemf appears to have been the first to advance a contrary 
opinion. At the end of a long paper mainly concerned with the morphology 
of the flower in the Cycads and the Conifers, he devotes less than two pages 
to the Grnetaceae, of which apparently he was able to study only the female 
flower of Ephedra distachya. He concludes that the outer envelope is the 
last product of the floral axis ; that it represents a single leaf, placed 
opposite to the subtending bract ; that it bears the unitegumented ovule on 
its ventral face ; that its edges are concrescent on the ventral side of the 
ovule which it encloses save for the apical aperture through which the 
micropylar tube of the inner envelope protrudes. This outer envelope is 
then an open carpel (ovuliferous scale) without style or stigma. This view 
is based entirely upon analogy with the Conif erae and the vascular structure ; 
the development of the parts concerned is not considered. A study of the 
development shows that this ovary or ovuliferous scale, like the inner 
envelope, is an outgrowth from the ovule which, according to Van Tieghem,. 
it bears ; further, it arises from two primordia % and represents two § or three || 
leaves, or from four primordia representing four leaves.^ If it is sought to 
extend this hypothesis to Gnetum and Welwitschia, the " ovuliferous scale " 
is not represented in the male flower of the latter — unless indeed the original 
inner envelope is concrescent with the nucellus** or is aborted,tt neither 
of which suggestions is supported by adequate evidence. In the case of 
Gnetum, Yan Tieghem's hypothesis necessitates the conclusion that the two 
outer envelopes of the complete female flower of Gnetum have different 
morphological values, which, in view of more recent evidence,:]:^ is impossible. 
* Ephedra : Eichler, 1863, p. 266; Strasburger, 1872, pp. 80, 83, 87, 235, Taf. xv,%. 
47 ; Bertrand, 1878, p. 65 ; Jaccard, 1894, p. 13; Arber and Parkin, 1908, pp 497, 504; (c/. 
also Thoday and Berridge, 1912, pp. 978, 979). Gnetum: Eichler, loc. ext.; Beccari, 
1877; Bertrand, loc. cit.; Strasbnrger, 1879, p. 107; Lotsy, 1899, p. 64; Arber and 
Parkin, loc. cit. ; Berridge, 1912, p. 991. Weltvitschia : Hooker, 1 863, pp. 23, 30 ; Eichler, 
loc. cit. ■ Strasbnrger, 1872, pp. 93, 94 ; Macnab, lb73, p. 507 ; Bertrand, loc. cit. ; Arber 
and Parkin, loc. cit. ; Pearson, 1909, p. 334 ; Sykes, 1910, p. 194 (but also see pp. 216,. 
221). 
t Van Tiegliem, 1869, p. 291. 
X Strasburger, 1872, Taf. xv, fig. 46. ,. ■ . 
§ Loc. cit., p, 235. ,. •; 
II Lignier and Tison, 1911, B. ' 
IF § Land, 1904, p. 8. . ; 
Sykes, 1910, p. 207. 
ft Strasburger, 1872, p. 150. ^ • .; 
XX Lignier and Tison, 1913. . . t 
