PLANT TAXONOMY (Identification, classification and description of plants)

The desert shrub known as jojoba, 

Simmondsia chinensis

, seems like a 

botanical joke. Name for a Mr. Simmonds and implying it comes from China, 

nothing could be farther from the truth as this shrub is only native to our 

desert southwest. Unfortunately, once a botanical name has been created, it 

cannot be changed because people don’t like it!

Finally, in the nomenclature system, we have to account for 

variation within species and other special categories

•

As mentioned previously, variable species are often given 
subspecific or varietal names. In this case, the varietal name is 
also italicized and starts with a lower case letter, but always 
follows the specific epithet

•

An example of how this works is with the Garry oak, 

Quercus 

garryana

, a tree common in Northern California

•

However, there is a shrub version of the same oak, and so it’s 
distinguished by adding the varietal name, giving you 

Quercus 

garryana breweri

.

Here is the full-sized “typical” 

Quercus garryana

a full-sized oak 

tree with a crown similar to other California oaks

Here in the left-hand corner is a stand of the dwarf Brewer’s oak, 

Q. garryana breweri

, similar to its tree sister except for size

Remember that cultivated varieties or cultivars are not the same 

as botanical varieties and so the rules for naming cultivars is 

different

•

Cultivar names are not italicized, are written inside single 
quotes, and should 

not

be in Latin although many break this 

rule

•

Cultivar names can often be two or three words long and 
usually describe some feature for which they’re named

•

For example, 

Arctostaphylos pajaroensis

‘Paradise’ is a 

particularly beautiful form of the species.

•

You will also often see a label with the genus named followed 
by a cultivar, without the specific epithet, such as 

Ceanothus

‘Dark Star’ This is often because the parentage of some 
cultivars is not known

Ceanothus

‘Dark Star’ is a great garden cultivar because it 

blooms long, has deep blue flowers, and doesn’t grow very tall. 

Although there’s no specific epithet, the species that at least 

entered this cultivar is 

C. impressus

Arctostaphylos pajaroensis

‘Paradise’ is garden worthy because 

it’s a moderate-sized shrub with pink tinted flowers and bronze 

new leaves.

This brings us to another important category in horticulture, 

hybrids

•

Technically, hybrids are genetic crosses between two different individuals, 
sometimes within the same species, but most often between two closely 
related species

•

Many hybrids may have “hybrid vigor” but fail to produce viable seed

•

The more distantly related the two parents, the less likely a hybrid will 
succeed

•

There are a few cases in which two genera have been hybridized, as in      

X 

Chiranthofremontia lenzii

. This hybrid is between the Mexican monkey 

hand tree (

Chiranthodendron pentadactylon

and the flannel bush or 

fremontia, 

Fremontodendron

. 

•

The orchids also have been widely hybridized between genera because in 
the wild, the parents are isolated by using different pollinators

California oaks sometimes hybridize where the habitats overlap. In this 

example, a black oak (

Quercus kelloggii

) has crossed with a coast live oak (

Q. 

agrifolia) 

to produce a hybrid that combines features from both species—

coast live oak is evergreen, black oak is deciduous, and the hybrid is 

half 

deciduous

!

Here is one of the parents of our bigeneric hybrid, the Mexican 

monkey hand tree with its cup-shaped dark red flowers and 

fingerlike stamens. The leaves are similar to fremontias.

By contrast, the California fremontias have saucer-shaped 
yellow-orange flowers with much less prominent stamens

And here is the hybrid, x 

Chiranthofremontia lenzii

. The flower 

shape recalls the Mexican relative but the color the California 

genus. Even the size of the plant is intermediate.

What’s the rule for naming hybrids? The unchanging rule is an x 

is placed in front of the specific epithet if it’s a hybrid between 

two species of the same genus but

•

If the hybrid is between two genera, the x goes in front of the 
genus name

•

In the case of our bigeneric hybrid we just looked at,  the 
genus name combines parts of the names of the two parents 
involved, while the specific epithet honors a man involved in 
making the hybrid

•

However, there are many hybrids where the parentage is not 
indicated by the hybrid name, as, for example, often happens 
in cultivars of hybrid origin

•

So just remember the x is the important part of a hybrid name