Camissonia hirtella (Greene) P.H.Raven
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Authority
Raven, Peter H. 1969. A revision of the genus Camissonia (Onagraceae). Contr. U. S. Natl. Herb. 37: 161-396.
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Family
Onagraceae
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Scientific Name
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Type
Lectotype: Mt. Hamilton, Santa Clara County, California, July 1891, E.L. Greene (ND).
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Description
Description - Erect annual, generally similar to C. micrantha, with one or more ascending branches from the basal rosette. Upper leaves narrowly ovate or ovate (rarely lanceolate), the apex acute, the base cordate to truncate. Inflorescence almost always with an understory of short glandular trichomes. Hypanthium 1-3 mm. long, 1-3 mm. across at the summit. Sepals 2.5-6 mm. long, 0.6-2 mm. wide. Petals 2-9 mm. long, 1.3-7 mm. wide, sometimes red-dotted near the base, occasionally with a salient tooth arising from the emarginate apex. Filaments of the episepalous stamens 1.2-6 mm. long, those of the epipetalous ones 0.5-3 mm. long; anthers 0.4-1 mm. long. Style 2-8 mm. long; stigma 0.5-1 mm. in diameter, surrounded by the anthers at anthesis. Capsule 0.75-0.0 mm. thick, terete, once or twice contorted. Gametic chromosome number, n=7. Autogamous, rarely cleistogamous.
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Discussion
As I conceive it, this taxon includes most of the populations generally referred to Oenothera micrantha var. jonesii (H. Lév.) Munz. As discussed under Camissonia micrantha, the tetraploid C. intermedia in part bridges the morphological hiatus between its two putative diploid parents, C. micrantha and C. hirtella, and thus renders the separation of all three taxa difficult. The chromosome number of Camissonia hirtella was determined in 84 individuals derived from 76 populations scattered throughout the range of this species (see Appendix). This widely distributed species is extremely variable in flower size, some individuals having petals up to 9 mm. long. Even in a collection with such large flowers, like R19076 (grown from R17402) from San Diego County, California, the longer set of anthers surrounds the stigma and deposits pollen directly on it, and the plants are fully self-compatible, setting a full complement of seed even when protected from insects. Insects are in general very rare at the flowers of this species. In addition to being one of the diploid parents of the tetraploid C. intermedia, Camissonia hirtella has very probably combined with the diploid C. pallida subsp. pallida to give rise to the tetraploid C. conjusa, and with one of these two tetraploids to give rise to the hexaploid C. luciae. Camissonia hirtella occurs sympatrically with C. bistorta, C micrantha, C. ignota, C. pallida subsp. pallida, C. intermedia, C. confusa, C. hardhamiae, C. luciae, and C. robusta. At times it is difficult to distinguish relatively narrow-leaved strains of this species from C. intermedia. For example, some populations from the central Sierra Nevada foothills of Calaveras County, California (e.g., Quick 52-01, CAS, 0.5 mile from Parrots Ferry bridge on road to Vallecito) , temporarily referred here, might actually prove to be C. intermedia if their chromosome number could be determined. Similarly, Heller 7337 (DS, F, GH, LE, NY, OSC, PH, KM, UC, US), a widely distributed gathering from the foothills west of Los Gatos, Santa Clara County, California, might belong to either species. Indeed, the existence of the tetraploid populations here referred to C. intermedia was the primary reason that plants as different as C. micrantha and C. hirtella could ever have been referred to a single species. Serious difficulty likewise exists in separating some of the large-flowered, southern California populations of C. hirtella from the geographically much more restricted tetraploid C. confusa. Camissonia confusa bridges the morphological hiatus between C. hirtella and C. pallida subsp. pallida in the same way that the other tetraploid known in the section, C. intermedia, bridges the gap between C. hirtella and C. micrantha. As C. hirtella is sometimes more similar to C. pallida subsp. pallida than it ever is to C. micrantha, the taxonomic problem can be even more serious, although the vast majority of populations can be assigned to one species or the other without difficulty. The three hexaploid species in the section can readily be separated from C. hirtella on the basis of the proportion of 4- and 5-pored pollen grains they possess. A single plant that was apparently a natural F1 hybrid between C. hirtella and C. ignota was found with the two parents in Lyons Valley, 8 miles northeast of Jamul, San Diego County, California. This plant had 6 pairs of chromosomes and 2 univalents in 2 cells and 5 pairs plus 4 univalents in 3 cells at diakinesis. It appeared to have set a full complement of seeds.