1907] CALDWELL— MICROCYCAS CALOCOMA 137 



in the seeds examined varying from three to six in number; usually 

 they are straight, but occasionally they are spirally twisted {jig. 42). 

 The seeds and seedlings secured were planted in the greenhouse and 

 are jiist now beginning to grow. After the root tip emerges and enters 

 the earth (fig, 4j), the cotyledons remain in the seed coat for a long 

 period, but its length was not determined. A tuberous stem several 

 centimeters in length is produced before other structures emerge 

 from the seed. The first true leaf, just now appearing in the green- 

 house material, is somewhat circinate, distinctly hairy, and arises 

 almost from the center of the stem {figs. 44^ 45). In the peculiarly 

 severe conditions in which Microcycas lives, there is often great danger 

 to the seedlings of dessication, and the production of a stout tuberous 

 stem before the production of leaves is evidently of great advantage. 



SUMMARY 



1. Small and wddely separated groups of Microcycas calocoma 

 occur in some of the mountains of western Cuba. 



2. The adult plant is a small tree, and reaches the greatest height 

 and circumference yet recorded for any cycad indigenous to the 

 western hemisphere. The stem may be a straight shaft or may 

 branch many times. 



3. The ovulate cone is the largest known; and it and its sporo- 

 phylls bear more resemblance to those of Zamia than to those of other 

 cycads. 



4. Unbranched vascular bundles pass up the stalk of the mega- 

 sporophyll, anastomose in the expanded portion, then give off five to 

 eight branches to each ovule. Immediately after entering the ovule 

 each branch divides, one subdivision passing unbranched through 

 the fleshy layer, and the other passing into the hard layer and branch- 

 ing many times. 



5. The staminate cone is long and slender, and two-thirds of the 

 abaxial side of its sporophylls is densely covered by sporangia which 

 do not show any distinct grouping into sori. 



6- In the male gametophyte eight body cells are formed and six- 



sperms 



Each body cell has two large blepharoplasts which 



side. 



opposite sides of the cell, but sometimes 

 mes nine or ten body 



