ARTIFICIAL VARIETIES UNDER NATURAL 



CONDITIONS 



Can the Bud Sports of the Boston Fern Thrive Under Conditions 



of Natural Selection? 



R. C. Benedict 



Brooklyn Botanic Garden. 



IN AN article pul^lished as a leaf- 

 let of the Brooklyn Botanic Gar- 

 den (Series X No. 3, 1922), the 

 suggestion was made that it would be 

 a matter of considerable interest to 

 determine experimentall}' whether any 

 of the horticultural forms of the Bos- 

 ton fern, produced by the artificial 

 selection of florists, would be able to 

 stand the test of natural conditions ; 

 in other words, whether they are fit 

 to survive on the basis of natural 

 selection. It was further suggested 

 that such a test might easily be made 

 by setting out, say in Florida, under 

 favorable wild conditions, a selection 

 of the stronger cultivated types. Fol- 

 lowing the distribution of the leaflet a 

 letter was received from Mr. Charles 

 T. Simpson of Little River, Florida, 

 which bears directl}- on the problem : 



Your letter of July i and the accom- 

 panying fern papers reached me in due 

 time but I am a very busy old man and 

 my eyes trouble me so I can read but 

 little. Today I have just glanced over the 

 papers which are very interesting. 



I have lived on this place, which has 

 a couple of acres of hammock, for twenty 

 years. When I came here Nephrolcpis 

 cxaltaia grew sparingly in a part of my 

 liammock and on the two cabbage palmettos. 



Perhaps twelve years ago, I cannot re- 

 member, I turned out of my slat house a 

 plant of the form you call IVhitinani into 

 a part of the hammock which had no 

 cxaltata. but not more than six or seven 

 rods from a patch of it. I think I put out 

 only a single plant, — certainly very few — 

 but now the Whitmaui covers irregularly 

 over two square rods of the floor of the 

 forest. It is a rather open hammock and 

 not so favorable for ferns as if it were 

 thick and damp. 



At least seventy-five per cent of these 

 ferns hold to the Whitmaui type fairly well. 



Now and then there is a pure (?) exaltata 

 and there are some intermediates. I am 

 enclosing a few specimens. It is possible 

 that spores from the cxaltata may have been 

 borne by wind or other means and lodged 

 among the Whitmaui; that they may have 

 grown and made some of the plain plants. 

 A few of the Whitmaui plants are grow- 

 ing naturally a short distance above ground 

 on trunks of trees, not more than a foot 



The accompanying illustration shows 

 the leaves sent in by Mr. Simpson. 

 As will be seen, they manifest variable 

 and irregular division from plain once- 

 pinnate to twice-pinnate. Typical 

 IVhifmani develops thick, plumy, thrice- 

 pinnate leaves under the best green- 

 house conditions, but when grown in 

 untoward circumstances, and especially 

 in reverting strains, it will produce 

 leaves of the type shown. It is not 

 to be expected that the dense leaves 

 of the favorable florists' environment. 

 — rich soil, absence of competition, 

 moist air, — would be reproduced un- 

 der open conditions of a drafty ham- 

 mock. 



It does not follow that the plants 

 showing only once-pinnate leaves are 

 necessarily, as suggested by Mr. Simp- 

 son, true wild cxaltata. The leaves 

 sent in appeared much too thin for the 

 wild type. In a reverting strain, IVhit- 

 inani will normally produce occasional 

 crowns with practically complete rever- 

 sion. I could duplicate the series of 

 leaves shown by a selection of leaves 

 from one pot of reverting Whitmani 

 in the Brooklyn Botanic Garden cul- 

 tures. The plain once-divided leaves 

 of such a plant of reverting Whitmani 



115 



