G. R, Wieland, liberally backed by the Carnegie Institution, a flood of light has been thrown on the morphology of an extinct group of Mesozoic gymnosperms, which it is possible to study with a ...

1. The stony layer in seeds of gymnosperms is integumental in origin as far as the integument extends, and in the angiosperms studied it is carpellary. In cycads both the outer and inner fleshy layers ...

Most modern gymnosperms—conifers and gingkoes, for instance—rely on the wind to spread their pollen. For some gymnosperms called cycads, insects serve as their pollen shuttle service, and did so long ...

The cycads are an unusual group of gymnosperms in that they are pollinated by insects rather than by wind. In a study of the Mexican cycad, Zamia furfuracea, pollination was found to be dependent on a ...