VANILLA 



VANlLLA (Spanish, little sheath or pod). OrchidAcece. 

 Vanilla. Climbing orchidswhose branched stems ascend 

 to a height of many feet. The nodes bear leaves or scales 

 and aerial roots in alternate arrangement. Fls. in axil- 

 lary racemes or spikes, without an involucre at the top 

 of the ovary; sepals and petals similar, spreading; la- 

 bellum united with the column, the limb enveloping the 

 upper portion of the latter; column not winged. About 

 20 species in the tropics. 



The most important species is V. planifolia, the Va- 

 nilla of commerce. It is a native of Mexico, but is now 

 widely cultivateil in tb.' West Iii.liis. .I:iva, Bourbon. 

 Mauritius an.l ..tl,.,- i.IarnN ..f tl,,. tn.,.;,-.. its chief 

 requirera,.-nt Ini,,- a li..t, .h.ii.i. rliniai,.. Thr plants are 

 propagatod hv lutiini^s varviiiL,- in lini;tU from 2 to 

 about 12 ft., the louder uul.s Ijliuk thu mure satisfac- 

 tory. These are either planted iu the ground or merely 

 tied to a tree so that they are not iu direct connection 

 with the earth. They soon send out aerial roots, by 

 which connection with the soil is established. They are 

 usually trained on trees so that the stems are supported 

 by the forked branches, but posts and trellises are also 

 used as supports. In most places where Vanilla culture 

 is carried on pollinating insects are lacking and the 

 flowers must be pollinated by hand. Plants bear their 

 first fruit about three years after setting. They then 

 continue to fruit for 30 or 40 years, bearing up to 50 

 pods annually. The Vanilla pods are picked before 

 they are ripe, and dried. The vanillin crystallizes on 

 the outside. For a full description of Vanilla cul- 

 ture and methods of curing the pods, see Bull. No. 

 21, U. S. Dept. of Agriculture, Div. of Botany, by S. J. 

 Galbraith. Vanillin is also made from other sources 

 by chemical means. The genus was monographed in 

 1896 by R. A. Rolfe in Journ. Linn. Soc, vol. 32. 



planifdiia, Andrews (V. nromnVion, Willd. in part). 

 Fig. 2G39. CosnioN Vanilla. Vanilla Bean (from 

 the pods). Tall climbing herbs with stout stems: 

 Ivs. thick, oblong -lanceolate, acuminate, with short, 

 stout petioles: fls. yellow, large, in axillary racemes of 

 20 or more blossoms; sepals and petals oblauceolate; 

 labellum trumpet-shaped, with small, reflexed, crenulate 

 lobes. Winter. A native of Mexico but widely cultivated 

 throughout the tropics and in greenhouses. B.JI. 7167. 

 L.B.C. 8:733. G.C. III. 25:213. Gn. 57, p. 35. 



aromfitica, Sw. Stem angular: Ivs. broadly ovate, 

 with a bluntish point, contracted .at the base: fls. green- 

 ish and white. Jamaica, Colombia, Trinidad. 



HErNKiCH Hasselbring. 



VAKIEG&TION. This term is usually applied to a 

 class of variations, especially in leaf coloration, in which 

 the leaves become striped, banded, spotted, blotched, 

 etc., with yellow, white, red and various other colors in 

 connection with the normal green of other portions of 

 the leaves. In the case of yellow and white variegation, 

 the term albinism is sometimes tised, especially when 

 the plants are largely marked with white or yellow, as 

 in Abutilon Sellowianum, Pelargonium sonale, and va- 

 riegated forms of Eiionymus Japonicus, Hydrangea 

 horlensis, Hedera Helix, Panax Vietorim and others. 



Among the dracseuas, caladiums and codiseums, be- 

 sides the white variegatiou, there are developed beauti- 

 ful reds, pinks, yellow, etc. A= n rnln. tlir trrm varie- 

 gation is not used in cases ..I - ' i ' ii in which 



only the surface of the leaf i- i . :i iiimanyof 



the begonias, sansevierias i N. (, , . jinl S. Zey- 



lanica], Alocasia cuprea,Ci^."- '/:,'/, and others. 

 Fig. 2641. In many .such plauts tlie markings are due 

 in part to hairs, scales, or air in the cuticle or epider- 

 mal cells, as in Sansevieria and Begonia. In some be- 

 gonias, many varieties of Calathea (as C. omata, var. 

 albo-lineata), etc., the epidermal cells develop decided 

 and definite color variation, though the changes do not 

 usually involve the mesophyll or inner cells of the leaf. 

 In some genera, however, especially Calathea, we find 

 all gradations between purely epidermal variegation and 

 changes involving the deeper layers of the leaf, as iu 

 C. Veitehii and C. Makoyana. The same is true of 



VARIEGATION 



1901 



many other genera. Different kinds of variegation are 

 shown in Figs. 2640-1. 



True variegations may be distinguished from ordinary 

 colorations, bleaching, chlorosis, etc., by the fact that 

 the colored areas are usually quite sharply defined. 

 They do not gradually blend into each other, but have 

 definite boundaries. Cells in the variegated areas are 

 found, as a rule, to contain the same chlorophyll bodies 

 (chromatophores) as the ordinary green cells of the 

 plant. However, in the variegated parts, the green color 

 is not developed, and the chromatophores are often 

 smaller or are somewhat swelled and vacuolate. In the 



2M0. Varieea 



case of chlorosis, due to the lack of iron, or yellowing 

 due to the lack of light, a leaf will quickly develop its 

 normal color if given the proper conditions. This is 

 not the case, however, in variegated leaves. While the 

 intensity of whatever color the chromatophores may 

 have can be varied by light and food, a variegated cell 

 can never be changed by these means to a normal cell. 



The chlorophyll granules (chromatophores) appear to 

 have lost entirely, in many cases, the power to make 

 starch and sugar from the carbonic acid gas in the air, 

 and in other cases this power is very greatly reduced. 

 In practically all eases, however, when the chromato- 

 phores are not destroyed, they retain the power to con- 

 vert sugar into starch and they thus store up starch in 

 their tissues from the sugar manufactured by the 

 healthy cells of the leaf. 



White or albino variegation is of course due to a lack 

 of any coloring in the chromatophores, and some- 

 times to the entire absence of these bodies. The cells 

 seem to have lost completely the power of making 

 chlorophyll. These albicant variegations are to be 

 looked upon as the more extreme forms of variegation, 

 and usually arise through a feeble or atrophied condi- 

 tion of the plant. Seedlings raised from parents both 

 of which are variegsited in this way are usually very 

 weak. High feeding and favorable conditions of 

 growth, while they will not cause a variegated plant to 

 return to its normal condition, will often stimulate the 

 development of a normal green shoot that takes mcst 

 of the nourishment and thus causes the starvation and 

 disappearance of the albicant parts. In other cases, as 

 in codiaeums, modified chlorophyll is made. Large yel- 

 lowish oil - like drops occur in the substance of *the 



