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Cryptantha is a genus of flowering plants with approximately 200 species. The name Cryptantha is derived from the Greek "cryptos," meaning hidden, and "anthos," meaning flower, referring to the cleistogamous (small, inconspicous, self-pollinating) flowers found in the first known species in the genus (Hickman 1993). Cryptantha species are distributed in western North America (ca. 134 species) and western South America (ca. 65 species), with at least three species - C. albida, C. circumscissa, and C. maritima - found on both continents. Members of the genus Cryptantha are characterized as annual, biennial, or perennial herbs with simple, opposite to spiral leaves. Stems, leaves, and calyces are typically covered with long, tapering trichomes, which may vary in length, texture, and morphology, described as hirsute, hispid, strigose, or bristle-like, the larger trichomes often with bulbous bases (sometimes described as "pustulate"). The infloresecence is typically terminal, being a helicoid cyme or a raceme or panicle of helicoid cymes. The flowers are bracteate or more commonly ebracteate. Flowers are actinomorphic (rotate) and bisexual; cleistogamous flowers are present in some taxa. The perianth is pentamerous and dichlamydeous (composed of a discrete calyx and corolla). The calyx is either aposepalous (consisting of five, distinct sepals) or synsepalous (having a basal tube and five calyx lobes); sepals or calyx lobes are usually linear. The calyx is typically accrescent, continuing to grow during fruit formation. The corolla (described as rotate or salverform) is sympetalous, with a basal tube and throat and a "flaring" (horizontally oriented) limb, the latter bearing five corolla lobes. The corolla typically has five, often yellowish, indentations near the top of the throat termed "fornices," presumed to function as pollination and nectar guides. Some taxa have a ring of five internally protruding pads of tissue near the based of the corolla tube termed "crests." Stamens are five and epipetalous. The ovary is superior, with two carpels, usually four ovules (two per carpel), and a single, undivided style. As with other members of the Boraginaceae s.s., during early ovary development, growth of a so-called "false" septum divides the locule of each carpel into two. The four locules that result from this division form independent ovary walls by vertical differential growth, resulting in a four-lobed ovary. Each of the four ovary lobes contains a single ovule. The style position is gynobasic. The four ovary lobes are attached to the sides of the style base, a roughly conical structure termed the gynobase, which bears at its apex the terete, portion of the style. (Note that the gynobase can be interpreted as a modified portion of the style base or as an outgrowth of the receptacle, in which it can be termed a "receptacular axis".) At maturity, each ovary lobe develops into a one-seeded mericarp unit, termed a nutlet. Four nutlets generally mature in each fruit, although the number may be reduced (to 3, 2, or 1) by abortion; remnants of the abortive ovary lobe(s) are typically present. Each mature nutlet is attached to the gynobase by means of a ridge of tissue on the side of the gynobase that inserts into a groove of the nutlet. Thus, the nutlets of Cryptantha species have a characteristic "ventral groove", which runs down the ventral (adaxial) face of the nutlet, often being 2-forked or opening into a triangular region at the base. The nutlets of Cryptantha's are variable in number (1-4), color, size, shape, and sculpturing. Nutlet sculpturing can be smooth (and shiny) or roughened by means of ridges or bumps, the surface variously described as papillate (bumps very small and fine), tuberculate/verrucose (bumps pronounced), or muricate (bumps relatively large and radially elongate to some degree). The fruit of Cryptantha spp. typically includes both the nutlets and the surrounding, accrescent calyx, the latter an accessory tissue. Once matured, the nutlets have various methods of dispersal. Some species have nutlets that detach at maturity from the gynobase, falling out of the calyx. Some species have calyces that abcise and retain the nutlets, which are dispersed when the calyx is shed. And some species use a combination of the two techinques, usually with three nutlets falling away from the gynobase and one nutlet remaining firmly attached. In the latter cases, the remaining nutlet can be either abaxial or adaxial. Table 1. Taxonomic Treatments of the Boraginaceae
Whether treated as a family (Boraginaceae s.s.) or subfamily (Boraginoideae), the taxa with a gynobasic style and schizocarpic nutlets have been grouped into tribes by various workers. Engler & Prantl (1897) recognized four tribes (in his Boraginoideae): Boragineae, Eritrichieae, Cynoglosseae, and Lithospermeae. Mabberley (1993) and Heywood (1993) recognized five tribes: Boragineae, Cynoglosseae, Echieae, Eritrichieae, and Lithospermeae. The differences between the tribes are primarily based on style and fruit characters. The Boragineae has a flat or barely convex style base and concave attachment surface to the nutlets. The Cynoglosseae has a more or less conical style base with the nutlet tips below the point of gynobasic attachment. The Lithospermeae (similar to the Boragineae) has a flat gynobasic attachment site for its nutlets. The Eritrichieae has a more or less conical style base with the tips of the nutlets above the point of attachment to the gynobase. The Echieae is the only tribe with zygomorphic flowers (Mabberley 1997). Taxonomic History of Cryptantha The main apomorphy the defines the genus Cryptantha as a natural, monophyletic group is the presence of the distinctive scar on the fruit. As previously mentioned, this scar is referred to as a ventral groove and is the scar of attachment to the central gynobase. Cryptantha species show considerable diversity in morphology of the nutlets, which can vary in number per fruit (1, 2, 3, or 4), size (<0.5 mm to >3 mm long), shape (lanceolate to widely ovate; apex acute, narrowly acute, or acuminate, the latter often termed "beaked"), margin (rounded, sharp-angled, ridged, or winged), and sculpturing pattern (smooth, papillate, tuberculate, and/or muricate). In addition, several species have heteromorphic nutlets, which exhibit variation within a fruit. For example, C. micromeres has one large, smooth nutlet and three smaller, tuberculate nutlets in each calyx. Cryptantha taxa can also differ in plant duration (annual, biennial, or perennial), root coloration (some taxa with a red to purple pigmentation), plant height/width, branching pattern, leaf morphology, inflorescence position (axillary or terminal), bract presence and morphology, trichome type(s), calyx size and shape, and corolla size and color. However, the overall appearance of Cryptantha plants can be very similar and can even be confused with closely related species, such as Plagiobothrys. In general, fruit morphological features are the primary taxonomic features used in keys and descriptions. Despite generally well-defined genera, species delimitation within the Boraginaceae are often problematic (Higgins 1979). Cryptantha is placed in the tribe Eritrichieae by most authors (Engler and Prantl 1897, Higgins 1971, Heywood 1993, Mabberley 1997). During the last century, treatments recognized three separate genera: Krynitzkia, Oreocarya, and Cryptantha. In Engler and Prantl's (1897) treatment Krynitzkia had been merged into Cryptantha, although Oreocarya was still considered a separate genus. That changed in 1926, when Payson, after examining some South American species, could not discern a clear distinction between these two genera and included Oreocarya as a sub-genus of Cryptantha. The placement of Oreocarya within Cryptantha is still disputed. In 1951, Abrams listed Oreocarya and Cryptantha as separate genera in his Illustrated Flora of the Pacific States: Washington, Oregon and California, following Johnston's (1924) monographic treatment of the group. A more recent treatment (Weber 1987) also Oreocarya as a separate genus. The author's reason for this is decidedly sparse; he states in his introduction "It is not necessary ... to produce detailed justification for adopting a particular taxonomic point of view," apparently as an all-encompassing defense against his adopting older taxonomic conventions in several groups (Weber 1987). Weber's elevation of Oreocarya to generic status has not been widely accepted by present-day workers in the group (Stermitz et al. 1993). Higgins (1971) divides Cryptantha into four sub-genera: Cryptantha, Oreocarya, Geocarya, and Krynitzkia. The species of sub-genus Oreocarya are grouped together largely by a lack of derived characters, although traditionally the subgenus is "thought to be monophyletic" (Higgins 1971). Sub-genus Cryptantha is so ill-defined Higgins gives no evolutionary novelties for the group; he believes the group to be polyphyletic (Higgins 1971). Sub-genus Geocarya is set apart because of its cleistogamous flowers, although some individuals in the sub-genus Cryptantha apparently have this feature as well (Higgins 1971). Sub-genus Krynitzkia is composed mostly of annuals with deciduous calyces, elongate cymes, reduced flowers, and "somewhat" heteromorphic nutlets (Higgins 1971). Higgins (1971) believes this latter group to be polyphyletic, "the species ... apparently having arisen independently from several perennial ancestors". There have been other taxonomic divisions within the genus over the years. Engler and Prantl (1897), who listed Oreocarya as a separate genus, recognized two sections within their "Cryptanthe:" Eucryptanthe and Pterygium. Abrams (1951) divided Cryptantha into twelve sub-generic groupings (not including Oreocarya, which he treated as a separate genus): Angustifoliae, Peterocaryae, Maritimae, Barbigerae, Muricatae, Ambiguae, Mohavenses, Graciles, Ramulosissimae, Leiocarpae, Flaccidae and Affines. In this Abrams was following Johnston's 1925 classification, although Johnston himself later acknowledged Oreocarya's sub-generic status within Cryptantha. Higgins (1971) attempted to evaluate Oreocarya's evolutionary history without using phylogenetic methods, and suggested the following "groups" for the sub-genus: jamesii, flava, stricta, nubigena, abata, caespitosa, humilis, virgata, setosissima, flavoculata, and elata. The names of the "groups" were based on the specific epithet of one of the species in the group. In summary, the infrageneric classification of Cryptantha is quite uncertain at this time. Molecular phylogenetic studies (currently being conducted by Kristen Hasenstab at San Diego State University) should shed light on this in the near future. Literature Cited Abrams, L. 1951. Illustrated flora of the Pacific States. Volume 3. Stanford, CA: Stanford University Press.
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