Economic and ecological problems brought by the invasion of non-native species can be prevented in part by identifying patterns in the invasion process. We tested hypotheses that address variation in the spatial, taxonomic, and temporal distributions of non-native floras in the large and diverse geographic area defined as California. Analyses reveal that in time, 79% of all non-native species will occur in disturbed habitat; polyploidy is not correlated with geographic spread; the Poaceae and Brassicaceae are the most broadly represented families across elevations; introductions increase from all geographic regions from 1925 to 1969, but more recently from Asia, Australia, Africa, South Africa, and South America; and more than 50% of all alien taxa recorded prior to 1925 have become widespread. Some taxa without native representatives contain some of the worst invaders in the flora, thus we suggest that control efforts should be directed to recent arrivals without native representation. Our conclusions support the need to control the spread of non-natives early in the invasion process but also emphasize the need to control invasions from a floristic perspective, both locally and regionally.

Variation in size class distributions along elevation gradients can indicate localized spatial expansion by tree populations inhabiting mountaintops. We searched for this pattern in northern foxtail pine (Pinus balfouriana Grev. & Balf. ssp. balfouriana) stands located in the Klamath Mountains of northern California. Data from 32 belt-transects placed within 16 foxtail pine stands were used to test the hypothesis that this species is expanding downslope locally. Nonmetric multidimensional scaling (NMS) illustrated that size class distributions could be grouped into four types: (1) those at low elevations on north and east aspects; (2) those at low elevations on south and west aspects; (3) those at high elevations on north and east aspects; (4) those at high elevations on south and west aspects. Low elevation transects had greater abundances of small trees, while high elevation transects had greater abundances of large trees. We interpreted this pattern as support for the hypothesis that foxtail pine is locally expanding downslope in the Klamath Mountains. Further analyses showed that NMS dimensions were correlated with estimates of tree density, species diversity, the importance of shade-tolerant conifers, and boulder cover. Moreover, the importance of shade-tolerant conifers was related to aspect, substrate type, boulder cover, and interactions among these variables. The pattern of those correlations suggests that several ecological and environmental factors affect the ability of foxtail pine to expand downslope through alleviation or alteration of competitive interactions. Those results provide an ecological context for climate-mediated range expansions and retractions in northern foxtail pine.

The patterns of vegetation and soils were documented in an approximately 20 km² area of fluvial terraces adjacent to the Santa Ana River in southwestern San Bernardino County, California. Within this area there are three terraces of differing elevations that were last disturbed during major flood events. The oldest terrace surfaces probably were last disturbed during the Agua Mansa flood of 1862, which disturbed or created many current geomorphic features of the Santa Ana River basin. The most recent disturbance of two other terraces was identified based on photographs of flooding events in 1938 and 1969. Principal component analysis identified three assemblages of species whose distribution corresponded to the three terraces that differed in elevation, soil texture, and age since last disturbance by flooding. Canonical correspondence analysis showed that the assemblages identified by PCA were highly correlated with changes in soil texture and organic matter. The most reliable indicator species were Heterotheca sessiliflora and Lepidospartum squamatum for the first assemblage (associated with the lowest terrace, and corresponding to early successional assemblages identified by other researchers); Salvia apiana and Senecio flaccidus for the second assemblage (associated with the intermediate terrace); and Artemisia californica, Opuntia parryi, and Stephanomeria pauciflora for the third assemblage (associated with the highest terrace). Eriastrum densifolium subsp. sanctorum, the rare Santa Ana River Woolly Star, was associated with the earlier phases of succession. The most important soil factor distinguishing these assemblages was the silt/clay content of the soil.

This study describes the distribution of species in a 21.6 ha inland salt marsh, consisting of three plant communities. The marsh community is along Leon Creek in the Diamond Y Spring Preserve in Pecos County near Fort Stockton, in western Texas (31°00.54′N, 102°55.49′W). From driest (highest elevation) to wettest (lowest elevation), the sequence is a Sporobolus airoides (alkali sacaton, Poaceae) grassland, a Distichlis spicata (saltgrass, Poaceae) grassland, and in the drainage a Schoenoplectus americanus (bulrush, Cyperaceae) marsh community. The communities were simple, with a total of 15 species found in the marsh. The mean plant cover in the salt marsh was 59%. The Sporobolus grassland covered 26% of the marsh and contained six species including S. airoides with 52 ± 36% cover and D. spicata with 13 ± 21% cover. The four other species were Helianthus paradoxus (Pecos or puzzle sunflower, Asteraceae), Suaeda calceoliformis (seepweed, Chenopodiaceae), Limonium limbatum (sea lavender, Plumbaginaceae), and Sesuvium verrucosum (sea purslane, Aizoaceae) (<5% cover each). The Distichlis grassland covered 50% of the marsh and contained nine species. Distichlis spicata had 50 ± 33% cover followed by H. paradoxus at 25 ± 25% cover, S. calceoliformis at 10 ± 19% and S. airoides at 6 ± 20%. The five other species were S. texanus (Texas sporobolus, Poaceae), Flaveria chlorifolia (yellow flaveria, Asteraceae), Juncus mexicanus (Mexican rush, Juncaceae), S. americanus and L. limbatum (<2% cover each). In the Schoenoplectus community that covered only 2% of the salt marsh, there were 11 species. High cover species included S. americanus at 39 ± 33%, D. spicata at 22 ± 34%, H. paradoxus at 11 ± 26%, and S. texanus at 9 ± 14%. Seven other species had cover values of one percent or less including S. calceoliformis, J. mexicanus, Samolus cuneatus (brookweed, Primulaceae), Spartina pectinata (prairie cordgrass, Poaceae), Heliotropium curassavicum (alkali heliotrope, Boraginaceae), Agalinis calycina (Leoncita false foxglove, Scrophulariaceae) and Eleocharis palustris (spikerush, Cyperaceae).

Changes are made in the nomenclature of species and subspecies in the genus Arctostaphylos (Ericaceae). In this study, the focus is on species found in the coast ranges of California. Changes are made in A. nortensis from the area around the Oregon border with California, in the A. nevadensis complex in the North Coast Ranges, in the A. nummularia complex of the north to central coast, in the A. tomentosa complex of the central coast to the Channel Islands, and in the A. hookeri and A. pilosula complex of the central coast. Also discussed are other changes presented elsewhere that will affect the Arctostaphylos treatment in the next edition of the Jepson Manual.

Additional measurements of leaves and flowers are reported for Psittacanthus angustifolius and P. pinicola from Central America and southern Mexico. Measurements for mature fruits and seeds of P. angustifolius are reported for the first time. Additional information on the phenology, host range, and distribution of these mistletoes is also reported.

Although Platanthera chorisiana (Orchidaceae) was reportedly collected in 1912 from Lake Serene (near Edmonds), Snohomish County, Washington State, no other information about this site or collection was known. Since this original collection, it has been collected three more times in the state. Because this State Threatened orchid has never been relocated at the Edmonds site, and because it does occur at Lake Serene, near Mount Index, Snohomish County, Washington State, I reviewed potentially relevant literature and archives starting with the collection year. I documented its collection at Lake Serene, near Mount Index. The 1912 specimen passed from Harry B. Hinman, the collector and a member of the Mountaineers, to Donovan Correll, in Texas. The orchid has persisted at Lake Serene, near Mount Index, for at least 90 yrs.

We describe a cycadeoid trunk from the Aptian Chickabally Member, Budden Canyon Formation in Ono, California. Our diagnosis of the specimen as a cycadeoid was initially based on the presence of mucilage canals in the pith and the structure of the secondary xylem. This determination was subsequently supported by recognition of the distinctive morphology of the surface of the primary body of eroded cycadeoid trunks. The latter may aid in the identification of otherwise enigmatic Mesozoic fossils. This specimen is the third cycadeoid to be reported from northern California and slightly extends the known geographic range of the group within the state.

We describe Frangula purshiana (DC.) Cooper subsp. ultramafica J. O. Sawyer & S. W. Edwards, an endemic to the Sierra Nevada in Plumas National Forest, and compare it with other subspecies of F. purshiana. We discuss the use of the generic names Frangula and Rhamnus in the California flora. We also make a new combination Frangula purshiana (DC.) Cooper subsp. annonifolia (Greene) J. O. Sawyer & S. W. Edwards.

Dalea analiliana is described as new from the vicinity of Yécora in the Sierra Madre Occidental of eastern Sonora, Mexico. This perennial is related to D. nelsonii Greene, but differs in its white flowers, the presence of glands on both surfaces of the leaflets, and its more northern distribution. Dalea analiliana occurs in open grasslands and along roadsides in oak and oak-pine forest habitats similar to those described for D. nelsonii.

Field studies and herbarium analyses of populations of Potentilla L. sect. Graciles (Rydb.) A. Nels. with atypical petiole vestiture result in the description of Potentilla gracilis Douglas ex Hook. var. owyheensis as a new variety, differing from var. elmeri and var. flabelliformis in having cottony-tomentose vestiture on the petioles instead of appressed to spreading straight hairs. The new variety grows in mid-montane meadows from the Owyhee Mountains in southwestern Idaho to the Ochoco Mountains in northeastern Oregon. It is conceivably of hybrid origin, with Potentilla breweri S. Watson providing the petiole vestiture that is otherwise unknown in Potentilla sect. Graciles. The study also resulted in the improved understanding of Potentilla bruceae Rydb. as a relatively coherent taxon centered in meadows around Lake Tahoe, California. As a result, Potentilla bruceae, Potentilla drummondii Lehm., and Potentilla breweri are recognized as distinct species, with Potentilla subvillosa Rydb. and Potentilla anomalofolia M. Peck as synonyms of Potentilla bruceae. Potentilla versicolor Rydb. is also recognized as a distinct species related to P. breweri but differing in having straight silky hairs rather than cottony tomentum.

Brodiaea santarosae (Themidaceae) is a new species from southwest Riverside County and immediately-adjacent Miller Mountain of San Diego County, CA. It is easily distinguished from other Brodiaea species in southern California by its large flowers and distinctive, variable staminodes; morphological analysis revealed 11 total differentiating characteristics. Brodiaea santarosae occurs only on or very close to the 8–11 million-year-old Santa Rosa Basalt. It has the smallest range of the southern California Brodiaeas, with just four known populations occupying only a small portion of a ∼40 km² area, plus a fifth small population disjunct by 11 km.

It has been speculated that the B. santarosae population is a hybrid swarm between B. filifolia and B. orcuttii, based solely on the appearance of the staminodes and filaments in selected flowers. This speculation was rejected due to the lack of sympatry between the three taxa and because specimens of B. santarosae have numerous characteristics that are not intermediate between the claimed parent taxa. In contrast, intermediate characteristics were seen in F1 specimens of B. filifolia X B. orcuttii discovered in San Marcos, CA, the only location where those species overlap.

We also report extensions to the length characteristics for both B. filifolia and B. orcuttii and demonstrate that two populations of B. filifolia previously thought to be hybrids are consistent with other B. filifolia populations.