The water-storing tubers of plants 



John W. Harshberger 

 (with plate 17) 



Recently there has been brought to the attention of the writer 

 a number of plants that produce water-storing organs of an inter- 

 esting morphologic character. They were examined in the fresh 

 condition in free-hand sections and a number of microchemic tests 

 were applied in order to ascertain the character of the respective 

 reserve materials. Two species of ferns, Nephrotics cordifolia 

 from the garden of Dr. P. P. Calvert and Nephrolepis davallioides 

 Kze. [N. acuminata (Houtt.) Kuhn] from the fernery of Mr. John 

 P. Morris, of Chestnut Hill, were examined in detail. Asparagus 



Sprengeri, a much cultivated species of asparagus, was also 

 studied. 



Nephrolepis cordifolia (L.) Presl. [N. tnberosa (Bory) Willd.] 

 is a fern which is often found in cultivation. It is easily mistaken 



for the 



N 



from that fern in 



having shorter fronds and the pinnules more closely crowded 

 together. It resembles N philippincnsis Hort.,* also found fre- 

 quently in cultivation. Nephrolepis cordifolia is said to occur in 



northern 



Japa 



west Africa and in the whole of tropical America, growing on the 



ground, as well as epiphytic on trees. It has short, thick rhizomes 



vered by broken-off leaf-bases and numerous strong branches 



are formed, some of which are developed in midsummer as fleshy 



s which are about the size of pigeon-eggs (plate 17, figure 

 )• lore exactly, a mature tuber measured by me was in three 



'pensions, twelve millimeters, twenty-eight millimeters, and three 

 m 'lhmeters. 



use to the plant in its epiphytic existence. Mrs. J 



of 



t 



__J_^_^Jacksonville, Florida, found tubers on a specimen of 



««*«■ , AtLEY ' in the Cyclopedia of American Horticulture, gives this (N. philippi- 

 cs) as probably belonging to N. exaltata. 

 T^Hrist. Die Farnkriuter der Erde, 288. 

 ' IUIGAN » Mrs. J. M. Tubers of Nephrolepis. Fern Bulletin 7 : 12. 1899. 



271 



