To him is credited the introduction of the ginkgo tree and the Lombardy poplar to America.
"The Colonial Architecture of Philadelphia"
Frank Cousins Phil M. Riley
Recognising, as some previous observers had already done, that the microspores of those Cryptogams in which two kinds of spore are developed, are equivalent to the pollen-grains of the higher plants, he further pointed out that fertilisation "in the Rhizocarpeae and Selaginellae takes place by free spermatozoa, and in the Coniferae by a pollen-tube, in the interior of which spermatozoa are probably formed"-a remarkable instance of prescience, for though spermatozoids have not been found in the Conifers proper, they were demonstrated in the allied groups Cycadaceae and ginkgo, in 1896, by the Japanese botanists Ikeno and Hirase.
"Darwin and Modern Science"
A.C. Seward and Others
We have still, in the Cycads and ginkgo, the transitional case, where the tube remains short, serves mainly as an anchor and water-reservoir, but yet is able, by its slight growth, to give the spermatozoids a "lift" in the right direction.
"Darwin and Modern Science"
A.C. Seward and Others