DOMESTICATED PLANTS — BLAYDES 333 



The vegetative or somatic segregation of mutant tissues from a chi- 

 maera often is not as readily accomplished as in geranium and Goleus. 

 Special methods may have to be employed, as described below, for 

 potato and Saiisevieria. Some years ago it was noted that in the com- 

 mon potato variety "Red Triumph" tubers could be found which had 

 irregular white areas surrounded by the usual red skin, as illustrated 

 by A and B of figure 38 (pi. 10). This seemed to indicate that at 

 least these particular tubers were chimaeras, usually of the periclinal 

 type, but by some anatomical deviation the mericlinal form might de- 

 velop, as shown for those with white areas in the skin. No bud that 

 was free of the red pigment was found isolated in the white areas. 

 Since the potato is propagated vegetatively from tuber cuttings hav- 

 ing at least one "eye" or bud, it seemed probable that the red-skin 

 character was transmitted to the new vegetative generation by the 

 outermost layers of embryonic cells in the stem tip of the bud. To 

 shorten a long story, the stem tips on numerous cuttings were "peeled" 

 and planted. Some cuttings survived the peeling treatment and de- 

 veloped as usual-appearing potato plants, but were slower in sprout- 

 ing. In late summer, when harvested, the tubers from most of the 

 treated plants were all variegated, and were interpreted as being meri- 

 clinal chimaeras. These probably resulted from incomplete removal 

 of all red tissue from the embryonic stem tip at the time of peeling. 

 A few plants bore tubers all of which were white (pi. 10, fig. 38, 0)^ 

 including the "eyes" or stem tips. During the following summer, cut- 

 tings from the white tubers were planted, all of which developed 

 plants bearing "White Triumph" potatoes. Two other varieties, 

 "Blue Victor" and "Blue Meshanoc," have been treated in a similar 

 way, resulting in a "White Victor" and a "White Meshanoc" potato. 



Bowstring-hemp or snakeplant {Sansevieria trifasciafa) (pi. 9, fig. 

 33) has been in cultivation as an ornamental for more than a century 

 and as a fiber plant in Africa for a much longer time. About 50 years 

 ago a variegated form, characterized by a golden-yellow border around 

 the leaf edge, was found in cultivation by a native tribe in the Belgian 

 Congo. It was named Sansevieria trifasciata var. laurentii^ and is 

 usually listed on the floral market as S. laurentii (pi. 9, fig. 34). This 

 variety is more popular today as a decorative plant than is the species. 

 The species (fig. 33) could propagate vegetatively from leaf cuttings 

 as well as from rhizome pieces having a stem tip. Soon after the varie- 

 gated variety {laurentii) was introduced as a house plant it was 

 learned that the variegated form could be propagated only from 

 rhizome cuttings. Wlicn leaves are used as propagules, nonvariegated 

 plants will result which are like the species as illustrated in figure 35 

 (pi. 9). This led to the inference that laurentii is a chimaera with 

 two genetically different tissues. That is, the golden-yellow tissue, 



