WESTERN A rborist Changes in tree names

Donald R. Hodel

ost cultivated In contrast, botanical names some- atic order that reflects evolutionary trees have one or more times change but they have several relationships among species, genera, common names and advantages. A botanical name for a and families, arborists can sometimes Mnearly all have one or more botanical species does not vary from place to glean or extrapolate additional in- names (a Latin binomial composed place, a species can have only one ac- formation from the name to enhance of first a genus name followed by a cepted botanical name and only that their knowledge about the culture and species name). Common names usu- species can have that name. Botanical management of a little-known tree, ally do not change but have several names are understood worldwide including growth patterns and prun- shortcomings. Common names for regardless of the spoken language, ing, pest and disease resistance, litter the same species can vary from place botanical names are often descriptive potential, esthetic qualities, and soil, to place, a species can have more than of the species and provide informa- nutritional, and water requirements, one common name and more than tion about the relationships of the tree simply from already knowing its close one species can share the same com- with related species, and there is a set relatives. mon name, common names may not be understood by those unversed in the language of the name, common One of the most frustrating aspects names frequently are not descriptive and can even be erroneous or mislead- of botanical names that confronts ing, common names typically provide no information about the systematic arborists is that they sometimes relationships of the tree with related species, and there are no rules govern- change. ing the use of common names. of rules or a code governing the use of Why botanical names change Figure 1. Platanus × hispanica is the botanical names. Thus, arborists and Three primary reasons are responsible new, accepted name for this tree related professionals frequently use for changes in botanical names and in Lakewood, CA that was formerly and rely on botanical names. two of the three are based entirely or known as Platanus × acerifolia. Unfortunately, one of the most partly on the concept or rule of prior- frustrating aspects of botanical names ity of publication of a name, which is that confront arborists is that they that the oldest, valid name usually is sometimes change. Changes in botani- the accepted name. The three reasons cal names of trees significantly impact that botanical names change are: arborists and other professionals in 1. ignorance of earlier names; the tree and landscape management 2. new interpretations and classifi- industries because they must learn cations of species and genera; new botanical names, change docu- 3. misidentification. ments, inventories, and databases to reflect the new names, prepare new Ignorance of earlier names labels and tags, and update references Sometimes plants end up with more and cross-reference old names. All than one botanical name, which is this work takes time and energy and not permitted according to the rules. has a cost associated with it. This situation usually happens when However, arborists and related a botanist names a new species not professionals will find it advanta- knowing that the species already geous to accept, learn, and use the has a valid, accepted name. In these new botanical names to ensure pre- cases, because of the rule of priority ciseness and ease of communication. of publication, the oldest name takes Also, because botanical names are priority and is the accepted name structured in an hierarchical, system- and later names become synonyms.

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Figure 2. (Above left) The new accepted name for this Chorisia speciosa in Los Angeles, CA is Ceiba speciosa. Figure 3. (Above right) All Callistemon were transferred to Melaleuca, so the new, accepted name for these Callistemon citrinus in Seal Beach, CA is Melaleuca citrina.

For example, the London plane tree, many botanists feel that all Michelia ent genus. If there is no existing genus Platanus × acerifolia (Fig. 1), a name (for example M. alba, M. champaca, and into which to place these segregate of which most of us are familiar, M. doltsopa) should also be transferred species, then a new genus must be was named and described in 1805. to Magnolia. erected for them. The transfer of some However, the same hybrid species In contrast, sometimes this new in- well known species of trumpet tree, was named and described as Platanus formation shows that some species in Tabebuia, to a new genus, Handroan- × hispanica 35 years earlier in 1770; a genus are more distantly related to thus, is an example. Thus the accepted thus, this earlier name, although not the other species, and they should be names for the yellow trumpet tree, well known, becomes the accepted separated out and placed in a differ- Tabebuia chrysotricha (Fig. 5), the pink name and P. × acerifolia is relegated to a synonym. Figure 4. (Below left) The new, accepted name for these Callistemon viminalis New interpretations and classifi- in Santa Barbara, CA is Melaleuca viminalis. cations Figure 5. (Below right) Some Tabebuia were transferred to Handroanthus, so Recent rapid advances of DNA se- the new accepted name for this Tabebuia chrysotricha in Bellflower, CA is Han- quencing and other molecular tech- droanthus chyrsotrichus. niques have allowed botanists to elicit and accumulate new information about how plants are evolutionarily related, which has led to new system- atic classifications of species and even genera and families. For example, new data has revealed that the floss silk tree, Chorisia speciosa (Fig. 2), and other species in the genus, are more closely related to trees in the genus Ceiba, so closely, in fact, that they should be included in Ceiba. Because Ceiba is the older name, it has priority and the species of Chorisia were re- cently transferred to Ceiba. Thus, Ceiba speciosa is now the accepted name and Chorisia speciosa is relegated to a synonym. Similarly, all Callistemon (Figs. 3-4) have been transferred to Melaleuca and all Talauma (for ex- ample T. hodgsonii) to Magnolia, and

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Figure 6. (Above left) The new, accepted name for this Tabebuia impetiginosa at The Arboretum in Arcadia, CA is Handro- anthus impetiginosus. Figure 7. (Above right). Some Eucalyptus were transferred to the new genus Corymbia, so the new, accepted name for these Eucalyptus citriodora in Lakewood, CA is Corymbia citriodora.

Table 1. Name Changes in Some of the More Common Landscape Trees

Common name Previous botanical name New, accepted botanical name bottlebrush Callistemon citrinus Melaleuca citrina weeping bottlebrush Callistemon viminalis Melaleuca viminalis floss silk tree Chorisia speciosa Ceiba speciosa white floss silk tree Chorisia insignis Ceiba insignis Monterey cypress Cupressus macrocarpa (Fig. 9) Hesperocyparis macrocarpa lemon-flowering gum Eucalyptus citriodora Corymbia citriodora red-flowering gum Eucalyptus ficifolia Corymbia ficifolia spotted gum Eucalyptus maculata Corymbia maculata London plane tree Platanus × acerifolia Platanus × hispanica fern pine Podocarpus gracilior Afrocarpus falcatus Chinese tallow tree Sapium sebiferum Triadica sebifera yellow trumpet tree Tabebuia chrysotricha Handroanthus chrysotrichus pink trumpet tree Tabebuia impetiginosa Handroanthus impetiginosus Montezuma cypress Taxodium mucronatum Taxodium huegelii (Fig. 11) Brisbane box Tristania conferta Lophostemon confertus (Fig. 12) water gum Tristania laurina Tristaniopsis laurina

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Figure 8. (Above left) The new, accepted name for this Eucalyptus ficifoliain Los Alamitos, CA is Corymbia ficifolia. Figure 9. (Above right) Hesperocyparis macrocarpa is the new, accepted name for this tree in Strybing Arboretum at Golden Gate Park in San Francisco, CA that was formerly known as Cupressus macrocarpa. trumpet tree, T. impetiginosa (Fig. 6), Acacia farnesiana]). However, a move is pytus calophylla) or hybrids between are now Handroanthus chrisotrichus afoot to retain the name Acacia for the the two species. and H. impetiginosus, respectively, African species, so the final word may In most cases of name changes and the two Tabebuia names are now not yet be in on this matter. described above just the genus name synonyms. Similarly, some of the best changed while the species name re- known eucalypts, the picturesque Misidentification mained the same. However, in some lemon-scented gum, Eucalyptus citrio- When plants are brought into cultiva- cases, such as with the fern pine (Fig. dora (Fig. 7), and the showy and color- tion they may have been misidentified 10) where Afrocarpus falcatus is now ful red-flowering gum,E. ficifolia( Fig. and given and grown under an er- the accepted name for what we once 8), have been transferred to the new roneous name. Once a plant appears called Podocarpus gracilior, both the genus Corymbia and are now known in cultivation and is associated with genus and species names changed. as Corymbia citriodora and C. ficifolia, a specific name, it is a difficult and respectively. sometimes lengthy process to have How to keep up to date with tree Similarly, the large genus Acacia the correct name accepted, even when names has been split into several genera, to the original name can be shown to be Arborists and related professionals the sometimes outraged consternation erroneous. For example, the brush can easily check on plant names and and angst of many botanists, horti- cherry is frequently but erroneously keep up to date with changes by visit- culturists, and arborists. Acacia has grown and sold as Syzygium panicu- ing one or more of the on-line plant been retained for most of the roughly latum, which is a rare species in Cali- data bases: 970 Australian species with only a fornia. The correct name for nearly 1. http://www.theplantlist.org/ few outliers in the Pacific Islands, all trees grown as the brush cherry in 2. http://www.ipni.org/index. Madagascar, and Asia. Segregate California is Syzygium australe. Simi- html genera from Acacia include Acaciella larly, recent work has revealed that 3. http://www.tropicos.org/ (15 species, Americas); Mariosousa (13 mostly only the red-flowering gums Home.aspx species, Americas, including the hand- of smaller habit and red flowers are 4. http://www.cpbr.gov.au/apni/ some, wispy, ghost-like M. willardiana actually Corymbia ficifolia (formerly 5. http://sciweb.nybg.org/Sci- [formerly Acacia willardiana]), Senegalia Eucalyptus ficifolia) while the larger ence2/vii2.asp (about 200 species, pantropical but trees with white, pink, or orange many in Africa), and Vachellia (pan- flowers that have been referred to C. On-line databases also exist for tropical, including the sweetly fra- ficifolia are really another species, C. specific groups of plants, like mono- grant V. farnesiana, [formerly known as calophylla (formerly known as Eucal- cots, palms, legumes, and Compositae

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Figure 10. (Above left) The new, accepted name for this Podocarpus gracilior in Downey, CA is Afrocarpus falcatus. Figure 11. (Above right) Taxodium huegelii is the new, accepted name for this tree at The Huntington in San Marino, CA that was formerly known as Taxodium mucronatum. Figure 12. (Below left) The new accepted name for this Tristania conferta in Monterey Park, CA is Lophostemon confertus.

(Sunflower family) among others. Ritter. M. 2011. A Californian’s Guide Keep in mind, though, that published to the Trees Among Us. Heyday, changes or new interpretations of Berkeley, CA. botanical names often take months or years to show up in on-line databases Donald R. Hodel is the Environ- and years to gain acceptance and mental and Landscape Horticul- common usage in the nursery and ture Advisor for the University of landscape industries. Table 1 sum- California Cooperative Extension marizes more recent botanical name in Los Angeles, a position he has changes in some of the more common held for 28 years. He develops landscape trees. and implements educational and applied research programs for the Acknowledgements professional tree and landscape I thank Matt Ritter for reviewing the management industries. In ad- manuscript and offering valuable dition to continuing his regular suggestions. series on palms, Don will shortly be initiating in these pages of References Western Arborist a new series on Ritter, M. 2011. Why plant names trees. . change. Pac. Hort. 72(2): 48-52. Photos by Donald R. Hodel.

Once a plant appears in cultivation and is associated with a specific name, it is a difficult and sometimes lengthy process to have the correct name accepted, even when the original name can be shown to be erroneous.

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