SYSTEMATIC BOTANY OF MAIZE, AND ITS ALLIES 



11 



it in that its branches are arranged spirally instead of 

 in two ranks. Occasionally the tassel is not branched, 

 but more often it shows secondary branching. The 

 size and amount of branching of the tassel are more 

 or less dependent on the vigor of the plant. The central 

 spike of the tassel is remarkable in that the paired spike- 

 lets are arranged in several rows, whereas the lateral 

 branches have the pairs of spikelets in two rows. 



The ear resembles the central portion of the spike in 

 that the paired spikelets are borne in several longitudinal 

 rows. This peculiar arrangement of central spike and 

 ear seems not to be homologous with the structure 

 among other grasses and presents one of the baffling 

 obstacles in the discovery of the origin of maize. The 

 husks of the ear are merely leaf sheaths, often with 

 somewhat reduced blades and ligules borne on very 

 short internodes below the pistillate spike. 



Fig. 1. — A, Pair of spikelets from a tassel of Independ- 

 ence !x5 diam. . This shows in the partially opened upper 

 spikelet. The glumes, G; the lemma of the upper floret, 

 L : the tip of the palea, P; and parts of the three 

 anthers, A. 



B, A semi-diagrammatic section through the same 

 floret, showing the glumes, G; the lemma of each floret, L; 

 the palea of each, P : the filaments of both sets of stamens, F; 

 the anthers of one floret, A; the rudiments of the aborted 

 pistils, P; and the position of one lodicule in each floret, 

 Lo. The filaments of the second floret are drawn as they 

 appear after the anthers have been extruded, cast their pol- 

 len, and fallen off. It should be noted, however, that the 

 upper floret generally develops first. 



In corn, as in other grasses (and in asters and chry- 

 santhemums with their allies), the unit of the inflor- 

 escence is not the single flower but a group of flowers. 

 In grasses this unit is the spikelet which generally con- 

 sists of a more or less short axis at or near the base and 

 on opposite sides of which are two glumes, bract-like 

 or scale-like structures, one slightly higher than the 

 other; and above these glumes one or more florets each 

 having an outer scale, the lemma, and an inner scale, 

 the palea, the latter inclosing the pistil and stamens 

 and two or three fleshy scales, the lodicules. All 

 variations from this typical spikelet are due to enhanced 

 development or abortion of some of the parts. In maize 

 and many of its allies the spikelets occur in pairs and 

 each contains two florets, or, at least, one complete 

 floret and the rudiment of a second. The staminate 



spikelet of maize (as shown in fig. 1) has one spikelet of 

 each pair pedicelled and the other sessile or nearly so. 

 The membranaceous but firm glumes are nearly of 

 equal length. The upper floret develops earlier than 

 the lower. The lemma and palea are hyaline and 

 nearly as long as the glumes. The two lodicules are 

 at the back of the floret, and help spread open the 

 glumes at time of flowering. There is a rudimentary 

 pistil. The pistillate spikelet (fig. 2) is ordinarily 

 greatly modified, the glumes being thick and fleshy 

 and not completely enclosing the other parts. The 

 lower floret is generally very rudimentary and the 

 lemma and palea of the upper floret are shorter than the 

 glumes. The lodicules of the upper floret are generally 

 not as well developed as those of the lower. 



There are numerous anomalies in maize inflor- 

 escences; perfect flowers occasionally being found, 



Gi-- 



C P2 



Fig. 2. — A, A single pistillate spikelet from young cob of 

 Adams Extra Early x7 ', diam. I, showing the lower portion 

 of the style (silk), St: the first and second glumes, G 1 and 

 G : ; and a small portion of the floral axis or cob, C. 



B, A semi-diagraminatic section of the same spike- 

 let (xlS diam.), showing the basal portion of the style, St; 

 the glumes, G 1 and G-; the lemma and palea of the aborted 

 floret, L : and P 1 : the aborted ovary (pistil' and stamen of 

 this floret, O 1 and S 1 ; the lemma and palea of the developed 

 upper floret, L c and P : : the fully developed ovary and 

 aborted stamen of the upper floret, O- and S-; and the 

 position of the cob, C. 



pistillate flowers in the tassel and staminate flowers 

 on the ear being more common. Spikelets of more 

 than two flowers are sometimes found; and in varieties 

 such as Country Gentleman both florets of each spikelet 

 are fully developed. 



The styles (silks) of the pistillate flowers are usually 

 receptive to pollen for two weeks or more after they 

 emerge from the husks. Although the lower flowers 

 start growth about a week before the upper ones, the 

 actual time of emergence of silk varies little more than 

 48 hours at most because of the distance that the lower 

 silks must grow. The shedding of pollen from a tassel 

 lasts from two or three days to as many weeks due to 

 the fact that the upper branches mature before the 

 lower ones, the tips before the base, and the lower 

 florets of each spikelet before the upper ones. 



While technically each grain is a true fruit — a 



