THE TAXONOMY OF CHENOPODIUM HIANS, C. INCOGNITUM, AND TEN NEW TAXA WITHIN THE NARROW- LEAVED CHENOPODIUM GROUP IN WESTERN NORTH AMERICA, WITH SPECIAL ATTENTION TO CALIFORNIA Authors: Nuri Benet-Pierce, and Michael G. Simpson Source: Madroño, 66(2) : 56-75 Published By: California Botanical Society URL: https://doi.org/10.3120/0024-9637-66.2.56 BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Complete website, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/terms-of-use. Usage of BioOne Complete content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Downloaded From: https://bioone.org/journals/Madroño on 07 Aug 2019 Terms of Use: https://bioone.org/terms-of-use Access provided by California Botanical Society MADRONO˜ , Vol. 66, No. 2, pp. 56–75, 2019 THE TAXONOMY OF CHENOPODIUM HIANS, C. INCOGNITUM, AND TEN NEW TAXA WITHIN THE NARROW-LEAVED CHENOPODIUM GROUP IN WESTERN NORTH AMERICA, WITH SPECIAL ATTENTION TO CALIFORNIA NURI BENET-PIERCE AND MICHAEL G. SIMPSON Department of Biology, San Diego State University San Diego, CA 92182 [email protected] ABSTRACT In our search to document the fruits of Chenopodium L. taxa in North America to assist identifications, and after demonstrating fruits to be stable and diagnostic, we here focus on the some of the ‘‘narrow-leaved’’ group taxa prevalent in the western part of the continent. For this study, we sampled and classified, employing fruit characters as the leading criteria for categorization, more than 500 herbarium collections of Chenopodium of western North America, with a special focus on California. We concentrated only on taxa with fruits with adherent pericarp and lanceolate to lance-ovate, entire, un-lobed, or basally lobed leaves. Here, we recommend the recognition anew of C. incognitum Wahl as a separate species from C. hians Standley and 10 new species of Chenopodium in California and nearby states of western North America. The recognition of these taxa contributes to an ongoing study of the taxonomy of native Chenopodium in California, where an in- depth local taxonomic treatment of the genus has never before been presented. Our classification is supported both by biogeographical distribution and morphological characters. Taxonomic keys are provided. Key Words: California, Chenopodiaceae, Chenopodium, fruits, North America, taxonomy. Comprehensive phylogenetic analyses (Fuentes- ecological niche in a climax community (Ladyman Baza´n et al. 2012a, b) have provided a revised 2006). classification of Chenopodium L. s.l., recognizing six All these difficulties have not made Chenopodium independent lineages: Chenopodium s.s., the largest particularly popular among botanists; thus, compre- and most diverse clade, Blitum L., Chenopodiastrum hensive treatments of Chenopodium in North Amer- S. Fuentes, Uotila, & Borsch, Dysphania R.Br., ica have been few. Standley (1916, 1917) produced Lipandra Moq., and Oxybasis Kar. & Kir. These probably the most extensive and thorough of the molecular studies are congruent with morphological early Chenopodium treatments. Standley (1917) de- features as well. However, Chenopodium s.s. includes scribed many new species of the genus from Arizona, many incompletely defined and poorly known taxa, New Mexico, and Nevada, but he then admitted: reaffirming its reputation as a difficult genus and ‘‘It is unfortunately true that the North American more recently again, as a very challenging group to species are still poorly understood, and that a resolve taxonomically (Sukhorukov et al. 2018). wholly satisfactory arrangement of them is appar- The notorious difficulty in distinguishing Cheno- ently not to be secured at present’’ podium using vegetative characters stems both from (pp. 413). the early dehiscence of the plant’s primary leaves, which are often shed prior to fruiting and absent in This outlook was further supported in Aellen’s many collections, and from a plant architecture that (1929) seminal Chenopodium study, which he entitled varies considerably with environmental factors. only a ‘‘Contribution. .’’ and by Aellen and Just These two issues are further complicated by the high (1943), who indicated its incomplete nature in plasticity of the leaves, to the point that different taxa stating: often appear vegetatively similar with few other ‘‘Obviously many American records will have to characters that can aid in identification. Therefore, be added in the future.’’ the assessment of observable differences in vegetative (pp. 47). characters has remained a highly subjective activity. In addition, many Chenopodium species are also of Similarly, Wahl (1954) called his major study intermittent or episodic appearance (Jellen et al. solely ‘‘A Preliminary study of the Genus Chenopo- 2011, Benet-Pierce, personal observations), fairly dium in North America’’ and he mostly focused on rare, and poorly known. It is still inconclusive if eastern North American species. While Wahl did add species of Chenopodium are highly dependent on two new species, Chenopodium incognitum Wahl and colonizing disturbed habitat only and disappear after C. foggii Wahl, to his taxonomic treatment and did more established plant species have gained a perma- collect in California, there was scant additional nent foothold, or if they also occupy a specialized examination of Chenopodium in the state. In addi- Downloaded From: https://bioone.org/journals/Madroño on 07 Aug 2019 Terms of Use: https://bioone.org/terms-of-use Access provided by California Botanical Society 2019] BENET-PIERCE AND SIMPSON: CHENOPODIUM TAXONOMY 57 tion, most of Standley’s (1916, 1917) species were ing of C. berlandieri Moq). This widely distributed never confirmed as occurring in California. taxon, reportedly twice domesticated in the North The next, and most recent comprehensive treat- American continent and part of native eastern North ment of Chenopodium, is that in the Flora of North American crop complex, is considered a critical America (Clemants and Mosyakin 2003). This potential genetic resource for adaptive improvement treatment brought new clarity to the genus. Howev- the South American crop quinoa (Chenopodium er, without presenting new criteria for their evalua- quinoa Willd.), which has worldwide importance tion, many taxa were placed in synonymy (e.g., C. (Jarvis et al. 2017; Brenner et al. 2019). incognitum see below), and the descriptions of most With our ongoing goal of clarifying the taxonomy recognized entities were left still too vague to permit of Chenopodium of the western North America, precise identifications. where so many species occur, we here focus on Except for our very recent studies (Benet-Pierce employing fruit characters, in addition to vegetative and Simpson 2010, 2014, 2017), no other native features, on a group treated before under the North American Chenopodium species had been designation ‘‘narrow-leaved’’. This term was applied described in the last 50 yrs, even with an enormous to four to seven species by workers in the complex number of collections. Instead of additions, some (Crawford and Reynolds 1974; Crawford 1975; taxa that had previously been described and named, Crawford and Julian 1976; Crawford and Wilson fell into synonymy, such as Chenopodium incognitum, 1979; La Duke and Crawford 1979) referring to taxa which has generally been viewed as a synonym of C. with marginally entire, unlobed or basally lobed, hians Standl. (e.g., Clemants and Mosyakin 2003). lanceolate or lance-ovate leaves. We have used fruits Many of the species in the C. neomexicanum Standl. as the primary classification tool, as they provide the complex, described by Standley and Aellen had also best characters for recognizing independent taxo- taxonomically disappeared, in part due to the nomic entities. Once diagnosed, these entities can be difficulty that botanists had to tell the plants apart correlated with vegetative features and biogeographic conclusively. We showed this was rectifiable with the ranges. These morphological studies are a necessary use of fruits and seeds (Benet-Pierce and Simpson preamble to future molecular and phylogeographic 2017). studies in the complex. Standley and Aellen were both well aware of the Of the species generally included in this narrow- importance of fruit characters to aid on the leaved group, we concentrate here only on the species discrimination and description of species, as they with an adherent pericarp, which have been identified used fruit and seed traits in their descriptions. Wahl, in California and most western states as Chenopodi- in particular, insisted on the importance of fruit um hians Standley, C. incognitum Wahl (if recog- characters considering them ‘‘of primary significance nized), or often as C. atrovirens Rydberg plants with in ‘separating interbreeding populations’. This is adherent pericarp. The pericarp, when adherent, is evident because of the