Systematics of Amsinckiinae (Boraginaceae): The Popcorn Flowers

      This is a website on the plant family Boraginaceae (sensu Weigend et al. 2014, Luebert et al. 2016, Hasenstab-Lehman 2017), subtribe Amsinckiinae, many members of which are commonly known as "Popcorn Flowers". The Amsinckiinae was referred to as subtribe Cryptanthinae (orginally Eucryptantheae Brand 1931:22) by others (Ovchinnikova 2009, Hasenstab-Lehman and Simpson 2012), but recent nomenclatural opinion is that Cryptanthinae Brand is illegitimate (given it was described originally with a "Eu-" prefix), and that the earliest available name for the clade is Amsinckiinae (originally Amsinckieae; Brand, 1931:204). Recent molecular work has demonstrated that the taxa of subtribe Amsinckiinae form a natural, monophyletic group (Schwarzer 2007,Hasenstab-Lehman and Simpson 2012) nested within tribe Cynoglosseae (Långström and Chase 2002, Weigend et al. 2010, Nazaire and Hufford 2012, Weigend et al. 2013, Cohen 2014, Chacón et al. 2016). There is a recent biogeographic study of the Boraginaceae, including the Amsinckiinae (Chacón et al. 2017).

     Recent molecular phylogenetic studies (Weigend et al. 2013, Otero et al. 2014, Cohen 2014, Chacón et al. 2016, Simpson et al. 2017) have demonstrated the need for an expansion of our Amsinckiinae clade to include the monotypic Dasynotus daubenmirei and some former New World members of Cynoglossum s.l., the latter now classified as the genera Adelinia (monotypic; Cohen 2015), Andersonglossum (Cohen 2015), and Oncaglossum (monotypic; Sutory' 2010). We suggest that the Amsinckiinae include these taxa, as accepted by Chacón et al. 2016. A recent study (Sutory' 2019) suggests that a newly named genus, Ailuroglossum (2 species), native to China, may be a close relative of Adelinia, Andersonglossum, and Oncaglossum, and may warrant placement in or near the Amsinckiinae.

      The Amsinckiinae Working Group and collaborators are working on the phylogenetic relationships of the taxa of this subtribe. The subtribe currently includes a total of 17 genera, 311 species, and 359 minimum ranked taxa (including varieties and subspecies; see table below). We have proposed a number of nomenclatural changes and anticipate more in the future; see Simpson et al. 2017. Our biogeographic analyses (Guilliams et al., 2017) of the Amsinckiinae support the occurence of 18 dispersal events from North America to South America.

1. Plants perennial; leaves relatively large, generally > 5 cm long; nutlets (3.5–)5–12 mm long
    2. Nutlets not glochidiate......Dasynotus daubenmirei (monotypic)
    2' Nutlets glochidiate
        3. Corollas green to lemon yellow to brown, inflorescences somewhat bracteate; plants of Mexico......Oncaglossum pringlei (monotypic)
        3' Corollas white to blue to red to purple, inflorescences ebracteate; plants of the U.S.A and Canada
            4. Cauline leaves petiolate, pedicels not recurved in fruit, stems glabrous......Adelinia grandis (monotypic)
            4' Cauline leaves sessile, pedicels recurved in fruit, stems pubescent......Andersonglossum
1' Plants annual, biennial, or perennial; leaves relatively small, generally < 5 cm long; nutlets < 5 mm long
    5. Fruits bur-like; sepals in fruit very unequal, upper 2 > others, partly fused, arched over 1 nutlet, with 5 to 10 stout prickles, each with hooked bristles, lower 3 sepals distinct; nutlets 2......Harpagonella
    5’ Fruits not burlike; sepals in fruit ± equal or, if unequal, upper 2 > others, distinct, not arched over 1 nutlet, without prickles but with hooked or straight trichomes; nutlets 1 to 4
        6. Mature nutlets generally 4, widely spreading
            7. Nutlets radial, collectively + shaped, all similar......Gruvelia
            7' Nutlets paired, bilateral, collectively X shaped), all similar or some dissimilar......Pectocarya
        6' Mature nutlets 1-4, generally erect
            8. Nutlets without ventral groove, generally with ventral ridge distal to attachment scar
                9. Corolla limbs and tubes bright yellow or orange; cotyledons 2-lobed......Amsinckia
                9' Corolla limbs and tubes white to cream colored; cotyledons not lobed
                    10. Cymules glomerate; nutlet attachment scars above nutlet middle......Sonnea
                    10’ Cymules generally elongate (glomerate in Amsinckiopsis); nutlet attachment scars between nutlet base and nutlet middle
                        11. Plant vestiture various, but not coarsely hirsute to hispid......Plagiobothrys
                        11' Plants coarsely hirsute to hispid
                               12. Cymules more or less glomerate; corolla limbs 4–7 mm wide; nutlet abaxial surfaces rugose and papillate......Amsinckiopsis kingii (monospecific)
                               12’ Cymules elongate; corolla limbs 1–3 mm wide; nutlet abaxial surfaces tessellate......Simpsonanthus jonesii (monotypic)
            8' Nutlets with ventral groove extending to apex or sub-apically; attachment scars generally recessed or depressed
                13. Plants annual, generally wider than tall, often rounded to cushionlike; taproots red or purple when dry (often staining herbarium paper); flower bracts present
                      14. Sepals fused proximally, tubular, tube circumscissile in fruit; gynobase < nutlet......Greeneocharis
                      14' Sepals distinct, intact in fruit; gynobase > nutlet......Eremocarya
                13' Plants annual, biennial, or perennial, generally taller than wide, rarely rounded to cushion–like; taproots usually not red or purple when dry; flower bracts absent or rarely present
                      15. Plants biennial or perennial; leaves basal or tufted; nutlets smooth, rugose, or scabrous, apex broadly rounded to obtuse, ventral groove apex well below nutlet apex......Oreocarya
                      15' Plants annual or rarely biennial or perennial; leaves generally cauline, rarely basal; nutlets smooth, papillate, tuberculate, or muricate, apex narrowly acute to acuminate,
                            ventral groove apex almost to nutlet apex
                            16. Corolla limbs bright yellow or orange; cotyledons 2-lobed......Amsinckia
                            16' Corolla limbs white; cotyledons not lobed (2-lobed in some South American Cryptantha)
                                  17. Plants annual, rarely biennial (possibly perennial in J. racemosa); flowers always chasmogamous; nutlets ovate, triangular-ovate, or lance-ovate, often heteromorphic in size
                                        and sculpturing, margin rounded or angled and then often narrowly ridged or winged, densely or sparsely tuberculate, tubercles usually whitish......Johnstonella
                                  17' Plants annual; flowers chasmogamous or cleistogamous; nutlets lanceolate, lance-ovate, or ovate, usually homomorphic, margin rounded or angled, not ridged or winged
                                        (except C. oxygona, C. cycloptera, and C. pterocarya), smooth or papillate/tuberculate, if tuberculate, tubercles generally not whitish......Cryptantha