62 IOWA ACADEMY OF SCIENCES. 



NORTH AMERICAN CYCADS. 



BY THOMAS H. M BRIDE. 



As is well known the Cycadaceae constitutes a small section of the feymnosper- 

 nious plants. They are therefore, related on the one hand to the Gnetaceoe or 

 joint-firs, and on the other to the Coniferce, the conifers, our familar pines, cedars, 

 firs and yews. The Cycads are, however, both in habit and structure quite unlike 

 in many ways, all other existent plants. Nevertheless the fruit is borne in cones as 

 in the Conifene, and their stems, such stems as they have, are full of a gummy, 

 resinous (?) sap, and the general structure of the wood, the disposition of the 

 medullary rays also resembles these features in some of the coarser grained larches. 

 On the other hand some of the Cycads, notably the species of the genus Cycas, 

 resemble in some respects the ferns, their leaves unrolling from the stem's top are 

 circinate in vernation. To Saporta Cycads have the appearance of small, low palms, 

 the trunk is so short and massive, supporting its crown of far-spreading leaves. 

 Again the roots of most Cycads are poorly developed and resemble those of the 

 Monocotyledones . Accordingly it may be said in a general way that Cycads are 

 plants having leaves like the ferns, cones like the conifers, stems lite the palms, and 

 roots like lilies or grasses. 



In days gone by these curious plants have been variously classified, accordingly 

 as an author in his description laid stress upon this or that feature of the confused 

 make-up. It must be said also in this general description that while most Cycads 

 are as has been said simple low stumps a foot or two high, there are species, nota- 

 bly the Moluccan, that have tall and branching trunks forty to fifty feet in height. 



The nature and habits of Cycads are fairly illustrated by Cycas revoluta, a 

 not uncommon species in our greenhouses, and by our native American species 

 Zaniia integrifolia, of which more is to be said presently. 



Miquel, a Dutch botanist as it appears studied the cycadaceous plants and pub- 

 lished his work as long ago as 1812. Sir Joseph Hooker's descriptions in Genera 

 Plantarum are drawn largely from Miquel's work. An abstract from Hooker 

 (Gen. PI.) is here presented for the better understanding of our subject. 



" Flowers dioecious strobilaceous, Perianth always wanting. In staminate 

 flowers the strobiles subterminal toward the apex of the trunk or caudex, generally 

 solitary, oblong, ovoid or cylindric, very rarely subglobose; scales thick, coriaceous, 

 alternately multiseriate, imbricate or vertically superposed and valvately united 

 bearing on the dorsal side the poUiniferous locules; these are arranged without 

 order, three or four in a place, sometimes stalked but generally sessile opening by 

 a slit and showing ellipsoidal pollen. The pistillate strobiles in Cycas have flat 

 pectinate elongate scales bearing two or more ovules on the margin ; in other genera 

 the scales are shorter, more or less peltate, and bear one ovule on each side of the 



