﻿VIRESCENCE OF OXALIS STRICTA. 



107 



Morren * who goes into details, applies the term phyllomorphy . 

 But Penzigt does not draw so sharp a line of distinction. 

 Ordinarily there is no need for this, since evidently numerous 

 cases exist where the two phenomena grade into each other, 

 as evinced by Penzig's phraseology. Besides, where vires- 

 cence in the stricter sense affects the entire flower, the result, 

 i. e., the non-production of seed, is the same. This was the 

 case in the virescenceof Lonicera Periclymenum mentioned by 

 Morren, something which I also have been able to constatate 

 during 1904, 1905 and 1906 on plants of L. sem'pervirens 

 cultivated in the Missouri Botanical Garden. But it is a 

 very different matter where virescence affects but a single 

 circle of floral envelopes. The other organs appear to be in 

 no way changed. The fertility of the flower is not impaired. 

 The abnormality is transmitted to the offspring. 



It would appear then that in Oxalis strida viridiflora we 

 have a variety, at once constant from seed, which differs from 

 the species in but one character. This character chiefly 

 finds expression in (1) the color of the petal, due to the 

 presence of chlorophyll granules, and (2) the texture of the 

 petal, due to an increase in the number of layers of cells. 

 Thus far this variety docs not seem to have spread in the 

 neighborhood of the type locality. But in the vicinity of 

 Belleville, 111., not far from St. Louis, my father, Dr. M. P. 

 Hus, during August, 1907, found three plants of what ap- 

 peared to be 0. strida with white petals and white and green 

 petals.! A microscopical examination confirmed the opinion 

 that but little, if any, chlorophyll would be found in the white 

 parts. The yeUow chromoplasts were not entirely absent 

 from all cells, but present in so small number as to be inef- 

 fective. This plant also will be taken into cultivation. 

 Crossing experiments undertaken this year will, during the 

 next, undoubtedly yield interesting results. 



* Morren, Ch. Les virescences distxnctes des phyllomorphies et cas 

 particulier d'une virescence de ch^vrefeuille. (Bull. Acad. Roy. Belg. 

 IV : 125. 1850). 



t Penzig, O. Pflanzen-Toratologie. 1 : xx. 1890. 



X A white-flowered form of O. violacea is sometimes found. 



