What's in a name?

The New Sunset Western Garden Book is out.  I hurried to buy it because I was told that there have been lots of changes in the way plants are classified and I want to be sure I am using the correct names in my blog posts.

Plants are like people in that they are classified in families and according to "race" as well as having their own names and nicknames.  The common English names are the nicknames.  These differ in different places where the plants are known, and also of course where different languages are spoken.  The Latin binomials are the official names of the plants.  These are based on the appearance of the plants and their earliest formal descriptions.  Some plants have had more than one official name.  For instance, two botanists may have registered official descriptions, and later the two "type" plants were discovered to be variations of the same species.  Or the plant may have been named, and more careful study shows it to have different characteristics than thought at first, so the name has been changed.

Now we come to genetics.  Plants occupying similar ecological niches may look similar, but have quite different DNA.  Soooo -- an international committee has reclassified plants according to their genetic similarity.  In general this doesn't affect the binomial names, except when what was thought to be one species is divided into two, or vice versa.  The new Sunset book uses the new classification.

This affects my postings in the following way -- "yuccas and their kin" turn out not all to be related.  Here is what has happened:

Aloes and agaves, which look much alike, are not related at all.  Not that they ever were.  Both aloes and agaves are broad leaf succulents which are often thorny.  Supposedly you can tell them apart by which way the lateral thorns curl.

Aloe striata 'Karasbergensis'

Aloes, which are originally natives of S. Africa, have been moved from the Liliaceae family to the Asphodelaceae family.  Looks can be deceiving.  An aloe doesn't look much like either a lily or an asphodel.

Agave franzosinii

Agaves, which are originally natives of the Americas, have been moved from the Agavaceae family to the Asparagacea family.  An agave doesn't look at all like the asparagus we buy at the grocery store.  However, there is a resemblance between asparagus and the stalk of an agave or yucca flower that hasn't yet opened.




Dasylirions, Hesperaloes, Nolinas, and Yuccas, which look much alike, were all in the Agavaceae family.  But reclassifying them with their closest relatives according to their DNA gives the following:

Dasylirion longissima

Dasylirions are now in the Asparagacaea family.

Hesperaloe parviflora

Hesperaloes are also in the Asparagacaea family.

Nolina matapensis

Nolina funifera

Nolinas remain in the Agavaceae family.  However this family is being discontinued, so the next version of the book may classify Nolinas differently.

Yucca rostrata

Yucca gloriosa 'Tiny Star'

Yuccas are in the Asparagacaea family.










It's more than a little confusing.  Plants of different families can look a lot alike, if they have adapted to similar ecological niches.  And -- plants of the same family cannot necessarily survive in the same ecological niche.  For example, Yucca gloriosa is not reliably hardy in Barstow but the 'Tiny Star' cultivar is winter hardy.   So it's important to know your plants and know your climate zone.  Barstow is in USDA zone 8a and Sunset zone 11.  And it is important to know the microclimates in your yard.