Cryptantha s.s. Taxonomy & Images

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Taxonomy of Cryptantha
(modified from Simpson and Hasenstab, 2009; Hasenstab-Lehman and Simpson 2012)

      Cryptantha Lehmann ex G. Don, commonly known as "popcorn flower" or "cat's eye," is a genus within the family Boraginaceae. The circumscription of this family has changed repeatedly over the last twenty years [Engler and Prantl 1897, Heywood et al. 2007, Gottschling et al. 2001, Angiosperm Phylogeny Group (APG II) 2003], with various authors recognizing either a broad or narrow family concept. Here we accept the APG II (2003) system of classification, which recognizes a broad Boraginaceae. As treated in this manner, the family may be divided into subfamilies Boraginoideae, Cordioideae, Eretioideae, Heliotropoideae, Hydrophylloideae, and (possibly) Lennoideae (see Stevens 2001 onwards). Despite these changes in classification, Cryptantha firmly belongs in subfamily Boraginoideae, characterized by an inflorescence that is a circinate, scorpioid cyme (Buys and Hilger 2003), a deeply 4–lobed ovary with a gynobasic style, and a fruit that is a schizocarp of nutlets.
     The genus name Cryptantha was first used by Johann Georg Christian Lehmann in a seed catalogue for the Hamburg Botanical Garden. In 1836, Fischer and Meyer used Lehmann's proposed name Cryptantha in association with two South American species, C. glomerata and C. microcapa, but with no formal genus diagnosis. In that same year, however, the name Cryptantha was validly published in the General System of Gardening and Botany by Don (1837), who provided the first formal diagnosis for the genus in association with the same two South American species (Johnston 1925). Thus, authorship of the genus should correctly be cited as Cryptantha Lehmann ex G. Don. Greene (1887a,b,c) was the first botanist to carefully study the borages of tribe Eritrichieae (within which Cryptantha has been classified), which are diverse in western North America. He authored several revisions of Eritricheae members, including Cryptantha, in a series of papers in the journal Pittonia. Green recognized the importance of classifying the group based on characters other than floral appearance, noticing the great variation in nutlet characteristics among members of this tribe. He expanded the genus Cryptantha to include North American species that had been placed in the genus Krynitzkia Fisch. & C.A. Mey. Greene’s circumscription of Cryptantha included strictly annual taxa with deciduous fruits. Additionally, Greene recognized several genera that are now treated as part of Cryptantha, including Oreocarya Greene,  Piptocalyx Torr. [=Greeneocharis Gürke & Harms], and Eremocarya Greene. The next major revision came in the dissertation research of the Boraginaceae expert I. M. Johnston in 1925. In this monographic treatment of the North American species of Cryptantha, the genus was circumscribed to include Eremocarya and Piptocalyx [=Greeneocharis]. Each species was revised and clarified in this work, with each of the 57 species placed into one of fifteen sections. Shortly after the publication of his dissertation, Johnston spent several months in South America. These studies, with new herbarium vouchers, led Johnston to conclude that the perennial Oreocarya species should also be included in Cryptantha to form one large, homogenous genus. In 1927, Johnston published treatments of South American Boraginaceae, recognizing Cryptantha as having three subgenera in South America: Krynitzkia, Geocarya, and Eucryptantha [=Cryptantha]. Also in 1927, Payson, who was working on a monograph of Oreocarya, agreed with Johnston that Oreocarya should be included in Cryptantha. Payson, following Johnston’s treatments, recognized four subgenera in Cryptantha: Oreocarya, Krynitzkia, Geocarya and Eucryptantha [=Cryptantha]. (See Table 1 for details of the characters used to circumscribe these subgenera, and their distributions.) Since the 1920s, systematists have made revisions among species and their relationships within Cryptantha, but the subgenera themselves have remained largely unchanged. Higgins, another expert on the perennial taxa, published a revised monograph of Oreocarya in 1971, and agreed with Johnston and Payson on the inclusion of Oreocarya within Cryptantha. However, the classification of Oreocarya has been contentious. For example, Abrams (1951) recognized Oreocarya as genus separate from Cryptantha in his Illustrated Flora of the Pacific States: Washington, Oregon and California. More recently, Weber (1987) also recognized Oreocarya at the genus level, giving no specific reason for his circumscription, but arguing that genera should consist only of species easily recognizable by suites of characters. However, most recent classifications follow the treatments of Johnston, Payson, and Higgins in circumscribing Cryptantha in the broad sense, as encompassing all four subgenera. For Southern California, these include the treatments of Cryptantha in Munz (1974), The Jepson Manual (W.A. Kelley and Wilken 1993), and the draft treatment for the second edition of The Jepson Manual (R.B. Kelley in prep).

Table 1. Subgenera of Cryptantha recognized by Johnston (1927) and Payson (1927).

    Subgenus                                                 Characters delineating subgenus

Plants with cleistogamous flowers.  Cleistogamous flowers similar to chasmogamic flowers, except for closed corolla. Cleistogamous flowers located in axiles of leaves and often throughout the inflorescence.
Restricted to South America.

Plants with cleistogamous flowers.  Basal cleistogamous flowers highly specialized into lenticular structures.
Restricted to South America.
Krynitzkia (incl. Eremocarya, Johnstonella, and Greeneocharis) Annual (rarely perennial or biennial) plants with only chasmogamous flowers. 
Distributed in North and South America.

Perennial or biennial herbs, with only chasmogamous flowers. 
Restricted to North America.

      However, Hasenstab-Lehman and Simpson (2012), in a recent phylogenetic analysis of Cryptantha and relatives (including taxa of Amsinckia, Pectocarya, and Plagiobothrys) concluded that Cryptantha as typically treated (e.g., Johnston 1925; Johnston 1927; Payson 1927; Higgins 1971; Zuloaga et al. 2008) is polyphyletic. The former authors proposed splitting Cryptantha s.l. into five genera: Cryptantha s.s. (121 species), Eremocarya (1 species), Greeneocharis (2 species), Johnstonella (13 species), and Oreocarya (62 species). The latter four genera are resurrected. The following is a key to these genera:

   Plants annual, gen wider than tall, often rounded to cushion-like; taproot red or purple when dry (often staining herbarium paper); floral bracts present
Calyx basally fused, tubular, tube circumscissile in fruit; gynobase < nutlet ................................................................................................................................................. Greeneocharis
Calyx of distinct sepals, intact in fruit; gynobase > nutlet ..................................................................................................................................................................................... Eremocarya
Plants annual, biennial, or perennial, gen taller than wide, rarely rounded to cushion–like; taproot usually not red or purple when dry; flower bracts absent or rarely present
Plants biennial or perennial; vegetative leaves basal or tufted; nutlets smooth, rugose, or scabrous, apically broadly rounded to obtuse, ventral groove
         apex well below nutlet apex ......................................................................................................................................................................................................................................... Oreocarya
Plants annual or rarely biennial or perennial; vegetative leaves gen. cauline, rarely basal; nutlets smooth, papillate, tuberculate, or muricate, apically
         narrowly acute to acuminate, ventral groove apex almost to nutlet apex
Plants annual, rarely biennial (perennial in J. racemosa); flowers always chasmogamous; nutlets ovate or triangular-ovate, often heteromorphic in
            size and sculpturing, margin angled (rarely rounded), often narrowly winged, densely or sparsely tuberculate, tubercles usually whitish ................................... Johnstonella
Plants annual; flowers chasmogamous or cleistogamous; nutlets lanceolate, lance-ovate, or ovate, usually homomorphic, margin rounded or angled, not winged (except
            C. oxygona, C. pterocarya with generally toothed to undulate wings), smooth or papillate/tuberculate, if tuberculate, tubercles gen. not whitish ................ Cryptantha s.s.

     Cryptantha s.s., which is now catalogued at 121 species, has an amphitropic distribution. A total of 54 species occur exclusively in western North America, with distributions from Alaska to southern Mexico, and as far east as Texas (Johnston 1925; Payson 1927; Higgins 1971; Mabberley 2008). A total of 69 species occur in western South America, in Peru, Chile, Bolivia, and east to Argentina (Reiche 1915; Johnston 1927; Schwarzer 2007; Zuloaga et al. in prep). Two species, C. albida and C. maritima, are distributed in both North and South America.
      Members of the genus are annual, biennial, or perennial herbs. Stems are simple to highly branched, generally ascending to erect, and densely covered in trichomes (Johnston 1925; Payson 1927; Munz and Keck 1959, 1968; Higgins 1971; W.A. Kelley and Wilken 1993, Mabberley 2008; R.B. Kelley in prep). Among annuals, the basal rosette is common early in development but is lost as the internodes of the aerial shoots (including inflorescence) elongate. Cauline leaves range from opposite to alternate in arrangement. Leaf shape is spatulate, lanceolate, oblanceolate, but most often linear. Leaves have acute to obtuse bases. Leaf vestiture is strigose, "rough hairy," or "bristled." The largest, relatively stout trichomes, which are often designated as bristles, often have bulbous bases, described as pustulate (giving a tessellate appearance to the leaf surface). These pustules are composed of epidermal cells arranged in a ring around the trichome base; the epidermal cells are elevated, opaque, and silicified and are thought to be cystolith in origin (Johnston 1925). The trichomes are most often translucent and white, but can be yellow-brown in some taxa. The inflorescence is characteristic of subfamily Boraginoideae, being a circinate, scorpioid cyme unit (often described as a helicoid cyme, but see Buys and Hilger 2003); however, the inflorescence structure is often obscured by short internodes and absence of floral bracts. The calyx, considered part of the fruiting unit, is accrescent, and continues to grow as the nutlets mature. The shape and fusion of the calyx, as well as calyx vestiture and orientation when the plant is in fruit, varies among taxa and is often used to distinguish them. Flowers are chasmogamous (opening and capable of cross-pollination) in most taxa, but may be cleistogamous (not opening and self-pollinated) in members of subgenera Cryptantha and Geocarya (modified into lenticular structures in the last). The corolla limb (the expanded portion above the corolla tube, containing the five lobes) ranges in size from less than 1 mm wide (measured across from lobe to lobe) to ca. 1 cm wide. Corollas are universally white and are rotate to salverform. The corolla tube is usually equal to the calyx in length and bears five epipetalous stamens. At the outer corolla throat, the tissue is invaginated, resulting in five pinched or folded regions, known as fornices. The fornices, which enclose the throat, can vary in size, shape, and color, but are often yellow and possibly function as nectar guides. Corolla lobes are ovate–oblong or suborbicular, ranging from widely spreading to ascending in chasmogamous species. As is characteristic of the subfamily Boraginoideae, the ovary is deeply four–lobed, with a gynobasic style arising from the base and center of the ovary lobes. The ovary lobes mature into 1–seeded units with hardened pericarps, termed nutlets. The number of nutlets that develop to maturity can vary from 1 to 4. The tissue between the ovary lobes, interpreted as either receptacular tissue or the style base, continues to elongate and differentiate during fruit maturation. This tissue is often called the gynobase and is that to which the nutlets are laterally attached at maturity. The gynobase is narrowly–pyramidal in form, elongating during fruit maturation. (Note that "fruit" is used here to include the nutlets and accompanying calyx.) Nutlets are generally ovate to lanceolate in shape. The fruits are generally deciduous, and the whole unit encased by the calyx will easily detach from the inflorescence. A few annual species (e.g., C. dumetorum, some varieties of C. pterocarya of North America) have fruits comprised of heteromorphic nutlets. Often, there are three smaller, easily detached nutlets, and one larger nutlet that is strongly adnate to the gynobase. The pericarp wall is variable in sculpturing and color. The attachment scar is generally a shallow, triangular areole (generally not rimmed or elevated), which is continuous with the ventral groove. When describing the ventral groove, morphologists generally consider the groove and attachment scar as one feature on the nutlet; thus the ventral groove is often described as being basally forked.

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