492 
Arber and Parkin . — Studies on the 
Historical. 
In addition to reviewing the attempts that have been made to determine 
the place of the Gnetaceae in phylogenetic schemes, it may also be inter- 
esting and instructive to follow briefly the positions assigned to the three 
genera in the chief natural systems of classification from the time of Linnaeus 
onwards. We shall be chiefly concerned with Ephedra and Gnetum. IVel- 
witschia ( Tumboa ) was not known until l86o. Sir Joseph Hooker, 1 three 
years later, by a thorough and masterly study of the material received from 
its discoverer, Dr. Welwitsch, unhesitatingly placed it in the Gnetaceae, as 
a new genus. Its position here has never since been questioned, and this 
conclusion is in reality, as we shall endeavour to show, the key to the status 
of the group. 
Tournefort 2 founded the genus Ephedra in 1703. He placed it in his 
eighteenth class, set apart for trees and shrubs with apetalous flowers, 
The class following this also contained apetalous arborescent plants, which 
were, however, distinguished by the fact that their individual flowers were 
arranged in catkins. Thus Ephedra was not included in the amentiferous 
group, though placed in close proximity to it. 
Linnaeus accepted Tournefort’s genus, Ephedra , and established a new 
one, Gnetum , 3 for the Malayan tree, first described by Rumphius under the 
name Gnemon domestical In the fragment of a natural system of classifi- 
cation 5 left by Linnaeus, Ephedra is placed in the fifteenth ..group, the 
Coniferae, following the genus Taxus. The name Gnetum naturally does not 
appear, for it had not at that time been established. Passing to the younger 
De Jussieu, the first botanist to leave to us a complete natural system, we 
find in his scheme that Gnetum 6 is put in the Urticae, the third order of his 
last class, the Apetalae. The order following contains the catkin genera, 
then comes the fifth order, the Coniferae, in which Ephedra finds a place. 
It is grouped with Casuarina and Taxus in the first section of the order, 
which is characterized by a staminiferous calyx. The other section, dis- 
tinguished by possessing staminiferous scales but no calyx, contains the 
plants now invariably included in the Coniferae. The two Gnetacean genera 
are thus set apart in different orders, the catkin family intervening. Ephedra , 
though placed in the Coniferae, is marked off, along with Taxus and 
Casuarina , as a distinct section. A point which deserves notice is De 
Jussieu’s recognition of the presence of a calyx. 
De Candolle, the next great systematist, in his c Theorie Elementaire 
de la Botanique ’, published in 1813, does not mention either Ephedra or 
G?ietum. Presumably in accordance with the opinions then current he 
1 Hooker (’63). 
3 Linnaeus (1767), p. 125. 
5 Linnaeus (1751), p. 28. 
2 Tournefort (1703), p. 53. 
4 Rumphius (1750), voi. i, p. 181, PI. 71. 
fi De Jussieu (1789), pp. 406 and 41 1. 
