58 



POPULAR SCIENCE MONTHLY 



Fig. 4. Staminate Flower of Corn 

 (Zeamays). 1, First empty glume ; 2, second 

 empty glume; 3, first flowering glume; 4, first 

 palet; 5, second flowering glume ; 6, second 

 palet; 7, lodicules. The upper flower matures 

 first, but the palet and glume are smaller 

 than in the lower flower. 



the leaf sheaths enclosing the ear. It is just as possible for the lateral 

 branches to develop pistillate flowers as for the central spike, and they 

 often do so. The accompanying photograph (Fig. 2) exhibits a case 



in which we have the central spike 

 and also the lateral branches devel- 

 oping pistillate flowers. But ordi- 

 narily in evolution when one por- 

 tion begins to develop it is at the 

 expense of other adjacent parts. 

 In such case, the development of 

 the central spike of the tassel is 

 accompanied by the disappearance 

 of the lateral branches. By remov- 

 ing the surrounding ' nubbins/ we 

 find that there is a normal ear in 

 the center. 



The central spike of the normal 

 tassel usually has from four to 

 eleven rows of spikelets in pairs, 

 making eight to twenty-two rows 

 of corn when developed, while the lateral branches usually have only 

 two rows of spikelets in pairs, making only four rows of grain when 

 well developed. 



It is interesting to note the morphological 

 changes which take place in the modification of 

 the staminate flower into the pistillate. The 

 staminate spikelets are borne in pairs (some- 

 times in threes), one sessile, the other pedicel- 

 late, the pairs alternating. As already stated, 

 the pairs of spikelets are borne in two rows on 

 the lateral branches, and in four to eleven rows 

 on the central spike of the tassel (Fig. 3). The 

 structure of the staminate spikelet is shown 

 in Fig. 4. The outer glumes enclose two ses- 

 sile flowers, and are 7-12-nerved; flowering 

 glumes are 3-5-nerved, the palet 2-keeled, 

 lodicules 2, fleshy and truncate. There is 

 usually more or less difference between the 

 upper and lower flowers in a spikelet ; the upper 

 flower matures first, and the palet is larger than 

 the glume, while in the lower flower the glume 

 is larger than the palet (Fig. 4). 



° x -i pedicellate spikelet shortens 



Ihe first tendency toward the development down until it becomes sessile, 

 of a pistillate flower is indicated by a shorten- d > The sessile flowers become 



1 J pistillate; e, both flowers be- 



ing of the pedicellate spikelet until it becomes come pistillate. 



Fig. 5. Modification of 

 a Pair of Staminate Spike- 

 lets into a Pair of Pistil- 

 late Spikelets, a, b, c. The 



