Without adequate data, the conservation and management of rare species is difficult and increasingly expensive. Taxonomic bias, or taxonomically driven disparities in knowledge, can further make the job of conservation difficult. Here, we ask: Is there a bias in the amount of research effort given to rare species in California compared to non-rare natives and non-native species? To answer this question, we quantified the amount of literature available on Google Scholar and the number of accessions deposited in GenBank for California's rare native plants, non-natives, and non-rare natives. To account for the differences in species ranges, we aggregated occurrence data for each species from GBIF to determine approximate ranges. We compared the amount of research published and accessions available amongst various rare native plant ranks, non-native, and non-rare native plants in California. In literature and genetic accessions, rare native species were under-represented compared to non-rare natives and non-natives, even after accounting for the differences in species range size. Furthermore, the more threatened a species is, the fewer pieces of both literature and accessions were found. Basic knowledge about rare species is necessary for their assessment and conservation. Without an understanding of life history, genetics, population dynamics, and range sizes, interventions to recover rare plant populations are difficult. Our results quantify the lack of research on rare plants and illuminate a challenge that should be addressed in future funding and research efforts.

There are 129 red-flowered species in western North America that fit the hummingbird pollination syndrome. Theory predicts that these flowers should produce a specific red color that is conspicuous to hummingbirds but not to bees. In a few well-studied cases, red flowers can be produced with pelargonidin, cyanidin, or both—sometimes complemented with the addition of yellow carotenoids and sometimes not. Which pigment combinations are most common in California and whether they affect conspicuousness to hummingbirds and bees remain unknown. To determine the taxonomic distribution of the pigments responsible for red hummingbird-pollinated flowers, we quantified the color of 36 red-flowered species with the hummingbird pollination syndrome, primarily native to California. Approximately 40% of the sampled species produce pelargonidin and carotenoids, 27% produce cyanidin with carotenoids, 25% produce pelargonidin without carotenoids, and the remaining 8% produce cyanidin without carotenoids. From a phylogenetic perspective, primary anthocyanidin type and the presence of carotenoids have evolved independently among these sampled red-flowered hummingbird species. The reflectance spectra from these four pigment categories are very similar (strongly absorbent in the ultraviolet and visible range up to ∼600 nm). Consequently, there are no significant differences in the conspicuousness among species in these four biochemical categories to hummingbirds, nor are they significantly different from one another from the perspective of bees. Chromatic contrast values were below the coarse detectability threshold for bees in 67% of species and the mean conspicuousness for bees, in all pigment categories, is also below this threshold. The average total anthocyanin concentration is approximately 2× higher in species without carotenoids in their flowers compared to those species with carotenoids suggesting there may be a trade-off between these two pigment categories in creating red flowers. It appears red hummingbird flowers in California utilize a range of types and amounts of pigments to converge on a relatively narrow, red adaptive peak in order to avoid detection by bees while remaining conspicuous to hummingbirds.