LINNEAN SOCIETY OF LONDOX. 5 1 



ABSTRACTS. 



Tlie Strobilus Tlieor}' of Angiospermous Descent. 

 By Jonx Parkix, M.A., F.L.S. ' 



[Bead 15tli Marel), 1923.] 



The author sees at present no sufficient reasons for abandoning or 

 seriously modifying the theory of the origin of Angiospernis 

 (Flowering Plants) brought before the Society in 1907 by the late 

 Dr, Newell Arber and himself (5). 



After this lapse of time it may not be without interest and one 

 trusts profitable to re-state shortly the tlieory, to further elaborate 

 ir, and to review it in the light of work since accomplished 

 bearing on it. 



lie-Ktaiement. In the first place the theory is based on the idea 

 that the Angiospernis constitute a monophyletic group. In the 

 second place the cohort, Ranales, is lield to contain families with 

 the least modified flowers. In a genei'al way, from such a type 

 of flower as is, for example, possessed by some of the Magnoliactoe 

 all other flowers are consid(M'ed to be derivable by reduction and 

 modification. A hermaphrodite flower, in short, with its membei's 

 indefinite in number, free from one another, borne spirally on a 

 long axis and arranged in a definite sequence on this axis, viz., 

 proceeding from below upwards first perianth members with no 

 clear separation into sepals and petals, then stamens, and finally 

 car[)els. We may speak of such a derivation of all Angiospermous 

 flowers as the Eanalinn Jn/pothesis — a hypothesis in the writer's 

 opinion almost amounting to a generalisation. 



A flo.ver sucli as the above is to all intents and purposes a 

 strobilus, but a strobilus of a special type to which we gave the 

 name of antliostrohllus on account of its being characteristic of 

 flowering ])hints. Such a strobihis is distinguished not onlv by 

 being bisexual, but also by having its microspoiophylls (stamens) 

 invariably placed on the axis below (morphoh)gically spealcing) 

 the megasporophylls (carpels), and further by having the whole 

 of these fertile organs subtended by a number of sterile members 

 constituting the perianth. 



With the exception of the Angiosperms the only known plants 

 which obviously possessed such a type of strobilus were the 

 extinct Bennettitales. We therefore definitely put forward the 

 view — Wieland and others had hinted at it — that of all known 

 fossil plants this group was the most closely related to the 

 Angios|)erms. The peculiar and very reduced nature of the 

 female part of the Beinieltitean cone debarred tracing any direct 



