Cultivar Is A Cultivated Variety

Most cultivars need to be cloned.

A plant ‘variety’ is a group within a species that exhibits distinguishing characteristics. A ‘cultivar’ is simply a cultivated variety. The first five letters of ‘cultivated’ merged with the first three letters of ‘variety’ to form the word ‘cultivar’. A variety should be self perpetuating to some degree, and may be naturally occurring. A cultivar perpetuates by unnatural means, and would go extinct otherwise.

Of course, the distinction between variety and cultivar is not always so obvious. Varieties of nasturtium were selected from plants that displayed desirable qualities. Seed of these varieties grows into plants that display the same qualities. However, without continued selection, some varieties eventually revert to a more feral state in only a few generation. They are not truly self perpetuating.

Most hybrid tomatoes are unable to perpetuate themselves naturally. Their seed is either not viable, or is very genetically variable. Genetically variable seed grows into plants that are very unlikely to produce fruit that is comparable to that which produced their own seed. Nonetheless, hybrid tomatoes grown from original (primary generation) seed are generally varieties rather than cultivars.

The distinction might be that they grow from seed. A plant that is cloned rather than grown from seed is a cultivar. Cloned plants can be grown from cutting, layering or grafting onto understock, but are genetically identical to the original. Some rare camellias grown now are genetically identical copies of original cultivars that were developed centuries ago. Their seed would not be the same.

Some cultivars developed from selective breeding. Others were random but appealingly distinctive plants in the wild or even in landscapes. Many originated as ‘sports’, which are mutant growths of otherwise normal plants. For example, some plants, on rare occasion, produce stems with variegated foliage. Cuttings taken from such variegated stems became popular variegated cultivars.

Seed from a variegated cultivar is very unlikely to produce more variegated plants.

Curb Mongrel

P91208Fruit trees, with few exceptions, have been extensively bred to produce the quality of fruit that we expect from them. Some are consequently genetically unstable, or at least less genetically stable than their wild ancestors were. Even if they never mutate or try to revert to a more stable state, they are very unlikely to produce seed that can develop into genetically similar trees.

In other words, they are not ‘true-to-type’. Their seed might grow into trees that produce fruit that resembles that of one of their ancestors, or of a pollinating parent tree. It is impossible to predict what fruit will be like until it actually develops.

That may take a while. Some seed grown fruit trees start out with juvenile growth, and take a few years to mature enough to bloom and produce fruit. Some types of avocado trees grow tall and lanky for a few years before they bloom. Most citrus are fruitless and wickedly thorny through their juvenile phase.

Grafted fruit trees or those grown from cuttings are true-to-type because they are genetically identical clones of their single parents. Cuttings and scions (for grafting) are made from adult growth, so do not need to mature through a juvenile phase.

The unpredictability of genetic variability is the main reason fruit trees are not often grown intentionally from seed. Juvenility might be the second main reason. However, neither of these two reasons prevents curb mongrels from growing wherever their seed lands, which is often next to sidewalks and curbs where cores and pits get discarded.

Curb mongrels generally get removed and disposed of, just like any other weed. It would be more practical to plant a known cultivar of fruit into a situation where such a tree is actually desired. Every once in a while, a curb mongrel appears where it is allowed to stay, and eventually produces fruit that justifies its preservation.

Well, that was not what happened with this curb mongrel apple tree that appeared adjacent to a patio used for outdoor dining. It was not compatible with the landscape, so got removed before it was able to produce any fruit. It looks like it was grafted, but only because someone tried to cut it down without removing the stump two years ago.

The problem now is that it came up with enough roots to survive relocation. It is not so easy to dispose of a tree with such potential, even though there is no way to know what its potential is until it fruits. It will get planted into a private garden and pruned back accordingly. If we had planned for it to be relocated, the process would have been delayed until it was defoliated.

If the fruit is of inferior quality, the tree can be removed and discarded. At least we tried. Alternatively, a desirable cultivar can be grafted onto it. In a home garden, no one needs to know that it is not a known understock (rootstock) cultivar. The foliage resembles that of ‘Red Delicious’, which makes sense for seed that likely originated from a commonly discarded core.

Horridculture – Bad Seed

P80317+California poppies are like no other wildflower. They are so perfectly bright orange, and look almost synthetically uniform in profusion, as if painted onto coastal plains and hillsides. They may be a bit more yellowish in some regions, or a bit deeper orange in others, but they are always bright and strikingly uniform.
Genetic variation is naturally very rare. I can remember hiking with my Pa up to the (lesser known) Portola Monument in the hills behind Montara, and finding a few pale white poppies, and even fewer pale purple poppies. It was like finding four leaf clovers! Genetic variants among California poppies are not quite as rare as four leaf clovers are, but finding a few of both white and purple was really strange. I never found a pink one though.
Nowadays, poppies can bloom in all sorts of shades and hues or orange, yellow, red, pink and soft purple, as well as creamy white. Some bloom with fluffy double flowers. Of course, all this variety is not natural. California poppies were bred to do this.
The potential problem with such breeding is that California poppy is naturally very prolific with seed. Any of these weirdly bred varieties could escape into the wild and interbreed with wild poppies, causing them to be more variable, and interfere with the ecosystem.
The problem is not just with California poppies. Many plants get bred extensively enough to interfere with how they behave in the wild if they happen to escape cultivation.
Fortunately for California poppies, the weird new varieties do not really get very far in the wild. The are not true-to-type, so revert back to their original bright orange in just a few generations, even without outside influence. If pollinators do not recognize their unfamiliar color and form, they are less likely to get pollinated to continue to tamper with the ecology. In fact, wild California poppies still have the advantage in that regard.
This yellow California poppy with an orange center is a second generation seedling, and is already halfway between the original yellow variety, and the wild orange.

Citrus And Avocado From Seed

71227Is it possible to grow citrus from seed? The quick and simple answer to that question is, “Yes.” After all, many cultivars of citrus were originally bred from other cultivars, and then grown from seed. But of course, this an overly simplified answer to an unrealistically simple question about a surprisingly complicated process. Perhaps a better question is “Should citrus be grown from seed?”.

Almost all citrus are grafted for a variety of reasons. Those that are not grafted are grown from cuttings only because they do not need whatever advantages understock (or rootstock) provides for their counterparts. Either way, they are all cloned by some form of vegetative propagation. This ensures that they are all genetically identical to their parents, without potential for genetic variation.

Citrus have been bred and developed so extensively that most types are very genetically variable. Those that are the most variable tend to produce fewer seeds, and might even be classified as seedless. Those with more seeds are probably more genetically stable. Nonetheless, it is impossible to predict if seed grown citrus will resemble their parents, or be something totally different.

Furthermore, citrus are cloned from ‘adult’ growth that is ready to bloom and develop fruit. Those grown from seed start out with vegetative ‘juvenile’ growth that will not bloom. Juvenile growth is typically more vigorous and thornier than adult growth, and possibly wickedly thorny! Some types of citrus outgrow their juvenile phase quite readily, while others may take several years to do so.

Avocado trees grown from seed exhibit some of the same difficulties. Although they lack thorns, they do grow very vigorously and very tall for quite a few years before they bloom. By the time they develop fruit, the fruit could be too high to reach, and quite different from the original.

Just because citrus and avocados can be grown from seed does not mean that they should be. However, different is not necessarily bad. Many seed grown avocado trees get pruned into


P80630KWhat are they doing out there, in those two pots in the island of such a vast parking lot? It is hard to say from this distance. They are so isolated. They might be happy and healthy summer blooming annuals. They might just be weeds. They could be plotting World domination. Plants can do some weird things in isolation.

Mexican fan palm is the most familiar palm in Los Angeles. Some know them as skydusters because they are so tall and lanky, and do not seem to have anything better to do than lazily brush against the undersides of clouds as they float by. In Los Angeles, there are not many clouds to keep them busy, and there is not even much smog anymore. Mexican fan palms certainly do not make much shade, and because they are so tall, their little shadows land in neighbors’ yards. They are so tall that you might be able to see them from wherever you are merely by looking towards Los Angeles. Instead of getting Frisbees and kites stuck in their canopies, they collect satellites. When they drop one of their big leaves, it burns up in the atmosphere.

In their natural environment, Mexican fan palm lives in a large and mostly contiguous native range (areas) in which individual colonies are not isolated for too long. Pollen gets shared rather thoroughly. Trees are consequently very similar throughout the range. Slight genetic variation is only perceptible in regions such as Los Angeles, where various groups of trees are grown from seed collected from various regions of the native range.P80630K+

Sometime in the ancient history of the specie, a few individuals decided to leave the rest of the herd and go live in isolation out in the adjacent deserts. They could only survive where there was a bit of water, so they inhabited any oasis they could find. This might have happened as some trees migrated up canyons that had perennial creeks flowing through them only to have the lower portion of the canyon go dry as outflow from above decreased. Seismic activity within the region has a way of altering the outflow of springs. Anyway, these more reclusive palms eventually became a separate species, or subspecies, or variety, depending on the botanist providing the information. This separate species (or subspecies or variety) is now known as the California fan palm, or the desert fan palm. It thrives on the hot and arid desert air, but is not very happy in milder and more humid coastal climates. (I am sorry that I do not have a good picture at the moment.)

Unlike Mexican fan palm that lives in a big contiguous range, California fan palms lives in small isolated colonies where they can not share their pollen freely with other colonies. Over thousands of years, each colony adapts to its specific environmental conditions. Genetic variation within colonies is not perceptible, but is quite obvious in landscape situations where trees grown from seed from different colonies can be compared.

California fan palm is much shorter and stouter than Mexican fan palm. It does not need to compete with too many other specie out in the desert. The trunks are straighter, and the canopies are fluffier. Unlike the very informal and relaxed Mexican fan palm, it is an excellent palm for formal landscapes. It is the specie that flanks the famous Palm Driveway at the Winchester House in San Jose. The only stipulation for these formal installations is that all the palms must be grown from the same batch of seeds procured from the same colony.

Cultivars Are The Real Cloned Mutants

80516thumbIt is not science fiction. It involves neither ninjas nor turtles. Cultivars really are mutant plants that can only be propagated by cloning. The word ‘cultivar’ is a portmanteau (two words combined into a single word) of ‘cultivated’ and ‘variety’. Unlike other varieties of plants that can be perpetuated by seed, cultivars must be cultivated by unnatural techniques to maintain their genetic distinction.

For example, ‘Alamo Fire’ is a variety of Texas bluebonnets with maroon flowers. The original seed were collected from a few naturally occurring variants with maroon flowers, and grown into more plants with maroon flowers, which provided more seed. No seed was collected from those that bloomed blue. By repeating this process of selection a few times, the variety was developed.

The variety ‘Alamo Fire’ is now sufficiently genetically stable to perpetuate itself, which means that subsequent generations will also bloom with maroon flowers. However, a few blue flowers might bloom in any generation; and unless they are weeded out before producing seed, they will eventually dominate until the entire colony reverts from maroon back to the more genetically stable blue.

‘Meyer’ lemon is an example of a cultivar. It must be propagated vegetatively by cuttings, or perhaps grafted onto understock. In other words, it must be cloned. It is a genetically unstable hybrid of a lemon and an orange, so plants grown from their seed would be very different from the parent. Many hybrids are so genetically unstable that they are sterile, and unable to produce viable seed.

Many variegated or dwarf cultivars of all sorts of plants are not hybrids, but are mutants. It is common for some arborvitaes to produce ‘sports’, which are simply mutant growth that is somehow different from the original growth. If a sport has a desirable characteristic, such as densely compact growth, variegation, or golden foliage, it can be cloned as a cultivar. Just like ‘Meyer’ lemon, a dwarf golden arborvitae is very unlikely to produce genetically similar seedlings.