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MISSOURI BOTANICAL GARDEN. 



kinds just described may be met with. The stomata arc 

 less numerous. 



The petal of 0. stricta viridijiora is green in color, and 

 obcordate, with an undulate margin. The distribution of the 

 vascular bundles is in accord with the outline of the petal. 

 The exterior surface shows a limited number of hairs. These 

 are situated along the margin of the tip. The large unicellular 

 thick-walled kind is most frequent. Next in frequency comes 

 the small, unicellular thin-walled hair. Multicellular hairs are 

 rare. The epidermal cells (fig. 4) entirely lack the projecting 

 ridges of the cell walls of the epidermal layer in normal petals. 

 While near the base the cells are longer than broad, near the 

 tip the cells are more or less isodiametric. Often the upper 

 surface of these cells forms blunt papillae. Stomata are 

 more numerous than on the normal petal of 0. stricta. On 

 the inner surface of the petal of the variety, there are no hairs 

 and the stomata are few. 



Thus far then, the petal of Oxalis stricta viridiflora differs 

 from the normal petal of Oxalis stricta in the following par- 

 ticulars, i. e., color, width, distribution of vascular bundles, 

 shape of the epidermal cells, absence of ridges in the latter, 

 number of stomata, and in the possession of hairs of the 

 unicellular, thin-walled type, as well as a slight increase in 

 the total number of hairs. But the internal structure shows 

 further differences. While the petal of 0. stricta is but a 

 few cells thick, that of the variety is much thicker, and the 

 tissue is composed of several layers of cells much smaller 

 than those of the epidermis. These small cells are filled with 

 chlorophyll granules. Any attempt to demonstrate the pre- 

 sence of xanthin in the cells of the petals of the green- 

 flowered variety was unsuccessful. 



Though in many respects the petals of this virescent form 

 approach the sepals in structure, they do not represent 

 marked sepalody as it is presented in certain Onagraceae,* 

 for example, while their shape, instead of approaching that 

 of the sepals, deviates widely from it. 



* Hus, Henri. Over sepalodie van de kroonbladen van Oenothera- 

 soorten. Avec un r^sum^ en langue fran9aise. (Botanisch Jaarboek. Gent. 



■"00 i^. 



