Abronia elliptica and Abronia fragrans are lovely, wonderfully fragrant species, commonly abundant along sandy trails in the high desert.  They can quickly be spotted with their attractive, often spreading masses of green leaves and large snow-ball flower heads.  On a calm day, their fragrance pulls you toward them.  There is no disputing their beauty, but there is some disagreement about their scientific classification and about their characteristics.

     Abronia elliptica and Abronia fragrans are recognized as two distinct species by Kartesz's BONAP, the Flora of North America, Colorado Flora, Flora of Colorado, and Flora Neomexicana III, but they are combined into A. fragrans by Welsh in his 5th edition of A Utah Flora. 

   The two species are commonly misidentified in a number of herbaria collections.

   The most agreed upon characteristic that separates the two as distinct species is the shape of the fruit. A number of experts even indicate that one really needs to see the plant in fruit to correctly identify it. For example the Flora of North America says, "Mature to near-mature fruits are usually required for identification of Abronia species because of the variation of vegetative structures within each taxon. Abronia appears to be in a state of active evolution."

   A. fragrans fruits are (in Weber's words) "thick-walled, hard, the wings leathery, not folded together".  A. elliptica fruits are (again in Weber's words): "thin-walled, delicate, the wings not rigid or stiff, 2 of them folded together to form a groove".

    (Note that the discussion is always about the shape of the "fruit", not the "seed". The fruits of Nyctaginaceae open and contain one seed.)  

   FNA further indicates that the fruit of A. fragrans is arrowhead-shaped versus heart-shaped in A. elliptica.

   The Intermountain Flora adds two more valuable fruit characteristics, agreed with by almost all floras:    

   1) Abronia fragrans fruits sometimes do not have wings and if they do have wings, the top of the wings of the mature fruit is not expanded into inflated pads.
   2) Abronia fragrans fruit wings have strongly raised reticulate veins.

   Click to see a photograph of the Abronia fragrans fruit and click again for another photograph of the Abronia fragrans fruit. In these two photographs you can see the raised veins. Especially in the second photograph, you can see that the wings are very thin from top to bottom; they are not wide, not expanded at the top.

  1) Abronia elliptica fruits have wings and they are wide/expanded at their top.

  2) Abronia elliptica fruit wings do not have strongly raised reticulate veins.

  You can see photographs of the fruits of both Abronia fragrans and Abronia elliptica in Ackerfield's Flora of Colorado, page 463.

  Click for the SEINet photographs and Flora of North America description of Abronia elliptica, and click again for Abronia fragrans. Be sure to look at the distribution map and the illustration.

  Also click to read Ackerfield and Jennings' "The Genus Abronia in Colorado...", which includes photographs of Abronia fruits.

  Another characteristic that separates the two Abronia species is the presence or absence of rhizomes: Intermountain Flora indicates that A. elliptica is "often" rhizomatous. (That characteristic is true of all of the Abronia pictured below.) Intermountain Flora also indicates that A. fragrans is "not rhizomatous". As noted below, expert botanist Bob Sivinski agrees with Intermountain Flora, as does Stan Welsh. The rhizomes are not mentioned in other regional floras or in the FNA.

    A personal communication to me from Bob Sivinski (expert New Mexico botanist) indicates that at least one of the photographs below (second from the bottom) does show A. elliptica, not A. fragrans, as evidenced at least by the close spreading of plants, probably from underground roots. Bob indicates that although "none of the floristic manuals say it...,  A. elliptica has branching underground stems in most cases - you just have to dig deeply to find them".  Welsh addresses this point: "Recognition of the occasional rhizomatous plants, which occur sporadically through the range of the species, at any taxonomic level seems unwarranted".

   The Flora of the Four Corners Region provides several other characteristics that separate the two species. Most other floras agree with some, if not all of the following:

  1) A. fragrans leaves can be up to 11 cm long, are green not glaucous, and are glandular hairy to densely hairy on both sides. The leaves of A. elliptica are up to 5.5 cm long, glaucous, and glabrous on the upper side, glandular hairy on the lower side.

   2) The perianth tube of A. fragrans is green, pink, red, or purple with a white limb. The perianth tube of A. elliptica is pink or green with a white limb (see especially the 4th photograph below).

    Stanley Welsh, author of A Utah Flora, disagrees with most of the above discussion. He indicates that A. fragrans is "tremendously variable", and although he recognizes that others have separated A. fragrans into two species (or into subspecies) especially on the basis of fruit, he indicates that both types of fruit can be found in the same head.  Welsh concludes that "the separation [into two species or subspecies] seems to be arbitrary and is not correlated with other features".