io$ ANCIENT PLANTS 



It appears that these huge complex leaflike struc- 

 tures were really stamens, but nevertheless they were 

 rolled up in the circinate form as are young fern leaves, 

 and as they unrolled and spread out round the central 

 cone they must have had the appearance of a whorl of 

 leaves (see fig. 72). 



This, in a few words, is the main general character 

 of the fructification. The most important features, on 

 which stress is laid, are the following. The association 

 of the male and -female structures on the same axis, with 

 the female part above the male. This arrangement is 



found only in the flowering 

 plants; the lower plants, 

 which have male and female 

 on the same cone, have them 

 mixed, or the female below, 

 and are in any case much 

 simpler in their entire or- 

 Fig. 73.-Diagram of Cross Section of o-ani7atinn The rnniral fnrni 



Bennettites Seed, with Embryo gamzailOn. ^ 1 ne COniCai lOmi 



of the axis is also important, 



«, Double-layered seed coat ;», crushed ■ i r ,. ^u ^ v ,. ' 



nucellus; cot., two cotyledons which ^^ ^^ ^ne laCt tnat It tCrmi- 



practicaiiy fill the seed. natcs in the Seed -bearing 



structures. 



The position of the individual seeds, each on the end 

 of a single stalk, is remarkable, as are the long-stalked 

 bracts whose shield-like ends join in the protection of 

 the seeds. These structures together give the cone 

 much of the appearance of a complex fruit of a flower- 

 ing plant, but the structure of the seeds themselves is 

 that of a simple Gymnosperm. 



In the seeds, however, was an embryo. In this they 

 differ from all known seeds of an earlier date, which, as 

 has been already noted (see p. T*]^, are always devoid of 

 one. This embryo is one of the most important features 

 of the plant. It had two cotyledons which filled the 

 seed space (see fig. 'j'^, and left almost no trace of the 

 endosperm. Reference to p. 112 will show that this is 

 an advance on the Cycad seed, which has a small em- 



