The variegated leaves
More and more often in nurseries we find plants, sometimes even the most common and widespread, with foliage of particular color, with pink, yellow, white streaks or zoning; in most cases these are not incredible genetic manipulations, in reality they are real mutations, which occur randomly in nature. In fact it sometimes happens that from a normal shrub with completely green foliage you can see a branch develop with some striped leaves, or that in a seedbed a pair of variegated foliage appears among thousands of small plants.
In these cases the nurseryman picks up the young seedlings or the cutting and cultivates them separately, giving rise to variegated varieties.
Sometimes it is a rarity, as in the case of variegated azaleas or pittosporum, in other cases, especially when it concerns some garden plants, the variegated varieties have the success that the green leaf varieties had not obtained, as happens for many plants apartment, such as begonia rex, bromeliad, calathea, hypoestes; the species diffused in nature of these plants generally have almost completely green foliage, through successive selections now the varieties that we find in the nursery almost always present zoning, streaks, very marked colors.
Some of these particular coloring plants are actually produced by selecting particular variegations on plants that already present in nature zoning or margins or veins in contrasting color. To achieve an even more particular and exotic effect.
As far as most variegated houseplants are concerned, cultivation treatments are now practically identical to those we offer to leaf varieties of a single color; this is because now the variegation has been so selected, that it practically has a stable and solid characteristic; moreover we are so used to cultivating the variegated leaf variety, that we already know the cultivation treatments to be lent. In the case of the calathea, for example, only the variegated varieties are sold, while the most natural varieties, with green leaves, are not particularly appreciated.
But also in the case of plants such as the schefflera or the ficus benjamin, the varieties with leaves with yellow stripes are so common, that every plant lover knows the most suitable cultivation treatments.
As for garden plants, many variegated plants are rarities, which are rarely found on the market, and are often the result of fewer selections than many houseplants.
Therefore, especially in these cases, it is good to know that plants with variegated, striped, marginal leaves are generally a little more demanding than green-leafed relatives; generally they are more easily subject to attack by insects, and sometimes even by fungi; therefore we will have to be careful to better follow the cultivation indications of the species we are cultivating: we avoid exposing our variegated azalea to stress due to water shortages or excesses and to deficiencies or excesses of sunlight, for example.
Special care must be taken in maintaining variegation; in fact it can often happen that a shrub with a variegated leaf begins to produce some branches with foliage without variegations. In these cases the part without variegation will immediately be more vigorous and rapidly developed, to the detriment of the variegated part. To prevent our shrubbery from becoming completely green over time, we will have to quickly remove the branches that have unmoliegated foliage, to prevent their growth.
It sometimes happens that the variegated variety is so weak that it must be grafted onto a more vigorous but not variegated rootstock; in these cases it is good to promptly remove any branching with leaves that are not variegated, to prevent the characteristics of the rootstock from taking over those of the grafted plant.
The success of variegated leaves
The plants with leaves of particular color have recently been enjoying great success, this "fashion" is certainly due also to the desire to cultivate a particular or unusual plant, which we do not see in the garden of our neighbors.
In fact, however, these plants also serve a landscape purpose; in fact, in many completely green borders, or in the dim corner, a plant with yellow or white streaks with a touch of light and color, even when it is not in bloom.
We avoid however to place too many variegated plants close to each other, otherwise we will start not being able to enjoy the variegation, indeed, over time we could get an excessively crowded garden of different colors.
Variegated leaves: Why are they variegated?
But why do some plants have variegated foliage?
As we said before, these are often completely fortuitous genetic mutations; the green color of the leaves is given by chlorophyll, which also allows the plants to live, synthesizing, thanks to the help of air and sunlight, the sugars they need as nourishment.
It sometimes happens that some leaf cells fail to produce this dye, visually this event results in white spots. Practically the streaks and the white spots correspond to the areas of the leaves without dye, and therefore unable to photosynthesis. The streaks of other colors, different from white, are instead caused by the presence of other pigments, which are not chlorophyll, for example the pink or red streaks are due to the anthocyanins.
In completely red-leafed plants the anthocyanins develop together with chlorophyll; for example some maples have dark red foliage, this color is caused by the concomitant presence of chlorophyll and anthocyanins.
The pink streaks are due instead to chlorophyll-free foliage which presents however in the cells of the anthocyanins, with a pink color.
In some succulents for example it happens by mutation that they become completely pink or white, or are born completely devoid of chlorophyll; in nature the chlorophyll-free seedlings would immediately die, unless they are grafted onto a green stem, which then produces sufficient nourishment to survive and to develop the chlorophyll-free plant. In reality in nurseries we find many of these succulents, of fuchsia, yellow or white color; in reality this profusion of mutant cacti is not due to the crazy nature, in fact it is small green plants that are bleached, through the use of various techniques, among which the simplest is to keep them completely in the dark.