We have a hedge that has red puffball blooms.This year, for the first time, we have a single white bloom among the red. It’s quite unusual.  I have attached pictures. Can you explain this?

— Antonia Salzman, Granada Hills

Your plant is Calliandra haematocephala or pink (even though flowers are more red than pink) powder puff.  I believe the white flower came from a “sport” which, in botany, refers to a mutation in a chromosome within a leaf or flower bud that results in an unexpected leaf, flower, or fruit.  Nectarine varieties, for example, began as peach tree sports.  Nectarines are fuzzless peaches, identical to peaches in every way except for a single mutated chromosome.

If you cloned or took a cutting from the stem from where your white flower is growing, you could possibly grow a plant with only white flowers.  In fact, there is a white-flowered variety of your Calliandra species known as ‘Alba’ that was probably produced from a sport mutation just like yours.

Many plants with variegated foliage are sports.  Often, however, the mutation that caused the sport is not strong enough to endure as the plant grows. The result is reversion to the green foliage form from which the sport derived.  A case in point is variegated Hawaiian elf schefflera (Schefflera arboricola ‘Variegata’).  New growth on mature plants typically reverts to green.

As long as we are talking about Calliandra, we cannot overlook one of our most fetching native plants.  It’s known as Baja fairy duster (Calliandra californica) due to its delicate whisk broom flowers.  Both pink powder puff (10 feet tall and wide at maturity) and Baja fairy duster (five feet tall and wide at maturity) may be grown as stand alone shrubs or trained up a trellis.  Baja fairy duster is renowned for its seemingly endless flower production.  Only for brief periods will you not find at least one or two blooms on display.

Grace Hampton, who gardens in Burbank, wrote to inquire about the sabra prickly pear cactus that grows in Israel and throughout the Mediterranean, wondering how it got there since it is native to Mexico.  This cactus arrived in the Mediterranean courtesy of Spanish explorers who brought back samples from their Mesoamerican expeditions.  Although both the fruit and the pads of this cactus (Opuntia ficus-indica) are edible, the Spanish had a different application in mind.  Their interest was in the red pigment that was found in the gut of white cochineal scale insects that attach themselves to prickly pear cactus pads.  If you have any of this cactus in your yard, you have probably noticed the presence of these sticky insects at one time or another.

From the time the Spanish arrived in Mexico in the 16th century, until the advent of synthetic dyes in the late 19th century, cochineal scales were the main source of red textile dye in America and Europe.

Spain had a monopoly on the cochineal dye market for about 250 years until scale-laden cactus pads were surreptitiously exported — by the French and Portuguese — to the Caribbean, the Canary Islands and Portugal.

Sessile female scales attach themselves to prickly pear cactus pads, stick their proboscises into the pads, and suck cactus sap for sustenance. In the process, they produce a rich scarlet pigment known as carminic acid. This metabolite is stored in the gut of the female scales, to be used in defending themselves from attacking ants.

Scale eggs are especially rich in carminic acid and the indigenous peoples who still produce traditional cochineal dye are astute in collecting the pregnant scales for maximum dye production.

Prior to the export of cochineal dye from Mexico to Europe, the main source of European red dye was the kermes scale, which had been utilized as a textile dye since biblical times. In the book of Exodus, the materials utilized in construction and furnishing of the desert Tabernacle included tola’at shani, literally translated as “scarlet worm,” since it was thought that the dye used in coloring the Tabernacle tapestries and other fabrics was derived from a worm.

Recent investigations of this subject by Israeli researchers proved that the scarlet worm was in fact a scale insect that feeds on the Mediterranean kermes oak (Quercus coccifera).

However, the scarlet dye produced by the Mexican cactus scale was eight times brighter than that produced by the Mediterranean oak tree scale, and so all red dye used in Europe was soon manufactured from the cactus scale.

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number of years ago, Nick Kurek from Granada Hills sent me simple instructions for readying prickly pear fruit (tunas) and pads (nopales) for eating.  “The flesh of cactus pears,” he wrote, “is sweet and flavorful but full of seeds.  Needles come off the fruit by rolling them in the dirt, and then they are peeled.”  As for the pads, “cut the young ones only, slice off the spines, dice them and then boil them with onions.  Serve either hot or cold.”

Tip of the Week: One of the real pleasures of living in the world of plants is that you are constantly learning new things.

I have been closely watching and studying plants for almost 40 years and never knew until a few days ago that fragrant orchids existed.  But then my ever helpful and vigilant wife was at the supermarket and encountered some fragrant Dendrobium orchids on display in the floral department and even photographed them for me.  So of course I had to investigate the subject.  And wouldn’t you know it?  At orchidsmadeeasy.com, there is a list of 11 fragrant orchids, not including the supermarket Dendrobium.

Perhaps the most famous among the list of fragrant orchids is Vanilla planifolia, the same plant from whose pods and seeds vanilla extract is made.  Vanilla is a vining orchid that grows up to thirty feet tall in its homeland of tropical Mexico and Central America.  In that habitat, vanilla is pollinated by hummingbirds and bees, but not very efficiently.  Production costs are high because flowers last one day and must be hand pollinated so that daily flower inspection and pollination  is necessary.  Also the vanilla extract must be aged for up to two years before its flavor is fully expressed.   Know you know why, after saffron, vanilla is the most labor-intensive and expensive spice.

You can grow a vanilla orchid as an indoor plant.  It’s a challenge but can be done.  It requires constant fertilization and is often a target of spider mites and mealybugs.  It also needs soil that is consistently moist so roots must be inspected frequently for root rot.  Vanilla orchids are readily available on eBay for $10-$50, depending on the size of the plant.