We present Part II of a catalogue documenting nonnative vascular plant taxa occurring spontaneously in California beyond those addressed in The Jepson Manual: Higher Plants of California (Hickman 1993). Here we document an additional 117 taxa occurring spontaneously in California that were not accounted for in Part I (Hrusa et al. 2002) or in The Jepson Manual. The catalogue was compiled from new collections by the authors and others, previously existing herbarium specimens, peer-reviewed publications, other printed reports, and direct communications with field botanists. Only reports backed by herbarium vouchers are accepted as adequately documented. Of the 117 taxa, 42 are fully or sparingly naturalized in relatively undisturbed wildland habitats, 14 are naturalized in non-wildlands (roadsides, fallow fields, croplands, other disturbed areas), 13 are tenuously established or locally persisting, 22 are weeds of greenhouse or other horticultural environments, 7 are presumed to be non-persisting casuals (waifs), and for 19 there is no current information. Taxa recorded as already being widely naturalized and/or potentially significant pests include Brachypodium sylvaticum, Cuscuta japonica, Danthonia decumbens, Glyceria declinata, Juncus usitatus, Melaleuca viminalis, Rytidosperma penicillatum, Verbena incompta and Zostera japonica.

Over the past century in California, the invasive weed Salsola tragus (russianthistle) has become a widespread and troublesome pest plant. Early attempts at biological control of russianthistle achieved only partial success. Efforts to improve effectiveness of renewed biocontrol efforts revealed that two distinct, often sympatric, genetic entities comprise what has been called Salsola tragus: Salsola tragus and Salsola ‘type B’. Efforts to identify and characterize ‘type B’ resulted in recognition of a third form, ‘type C’. We present a taxonomic and morphological examination of Salsola tragus, Salsola ‘type B’, Salsola ‘type C’ and Salsola paulsenii using discriminant analysis with DNA sequence genotypes as the taxonomic framework. Salsola tragus and ‘type B’ were morphologically distinct; ‘type C’ was morphologically intermediate between them and contained DNA sequence genotypes that were an additive mixture of haplotypes mostly exclusive to tetraploid S. tragus and others exclusive to diploid ‘type B’. ‘Type C’ is a fertile allohexaploid that originated via hybridization between S. tragus and ‘type B’. We provide a pre-existing name, Salsola australis, for ‘type B’, and propose Salsola ryanii sp. nov. for ‘type C’. Morphological variation, habitats, and dispersal behaviors among these Salsola taxa were examined in the herbarium and in the field. These are compared and discussed.

Isozyme analysis of the rare Oenothera wolfii (Wolf's evening primrose) and the garden escape, O. glazioviana, indicates that hybridization between these species may be more widespread than morphological evidence indicates. Although both species contained low amounts of genetic variation, unique alleles were identified in both taxa. Analysis of 22 populations, including pure populations of each species, identified eight populations as containing putative hybrid individuals. Four of these putative hybrid populations were considered pure O. wolfii based on morphological analysis. This study confirms that the native O. wolfii may be at risk not only from habitat destruction, but potentially from genetic swamping where it co-occurs with O. glazioviana. These results can be used as baseline information for future genetic monitoring efforts.

C₄ photosynthesis without Kranz anatomy (single-cell C₄ photosynthesis) occurs in only 0.003% of known species of C₄ flowering plants. To add insight into the evolution of C₄ photosynthesis, we studied the tribe Orcuttieae (Poaceae: Chloridoideae), which has species that can grow under both aquatic and terrestrial conditions, and utilize single-cell C₄ photosynthesis when growing submerged. Carbon isotope ratios from aquatic, floating, and terrestrial leaves were in the range −12.25 to −14.31, suggesting that all species carry out C₄ photosynthesis. Using light microscopy, we examined the anatomy of aquatic, floating and terrestrial leaves from eight of the nine species in the tribe to assess the pattern of evolution of C₄ photosynthesis and Kranz anatomy among these vernal pool grasses. Kranz anatomy was present in all floating and terrestrial leaves of Orcuttia californica, O. inaequalis, O. pilosa, O. tenuis, O. viscida,Tuctoria greenei, T. mucronata, and Neostapfia colusana. Although carbon isotope data indicated C₄ photosynthesis, aquatic leaves of all members of Orcuttia lacked Kranz anatomy, while aquatic leaves of Tuctoria and Neostapfia possessed Kranz anatomy. When considered in a phylogenetic context, these findings support previously proposed hypotheses suggesting that Orcuttieae are derived from a terrestrial ancestor and are now becoming more specialized to an aquatic environment.

Rare, parasitic plants pose an interesting challenge to restoration practitioners. In addition to the problems associated with small population size, rare parasites may also be limited by their host requirements. We examined how the performance of a rare Pacific Northwest hemiparasite, Castilleja levisecta, was affected by the availability of different host combinations in the greenhouse and in the field. Castilleja levisecta individuals were grown with two individuals of the grass Festuca roemeri, two individuals of the aster Eriophyllum lanatum, one individual of each of these species (a “mixed” treatment), or without any host. We did not find support for the complimentary diet hypothesis, which predicts that parasites grown with multiple host species perform better than individuals grown alone or with a single host. In the greenhouse, C. levisecta individuals grown in the mixed treatment had greater stem growth than those planted with F. roemeri, but did not differ from E. lanatum or no-host treatments. In the field, vole activity had indirect effects on C. levisecta survival mediated through host species: vole tunneling and C. levisecta mortality were strongly associated with host treatments including E. lanatum. Vole tunneling and C. levisecta mortality were strongly associated with host treatments including E. lanatum. Field survival of no-host and F. roemeri treatments were significantly higher than those grown with E. lanatum. Our results emphasize the importance of basing conservation decisions on experimental research conducted under conditions similar to those of the intended application, as greenhouse results were a poor predictor of field performance. For restoration of endangered hemiparasitic plants, we recommend planting with hosts that are not attractive to herbivores.

A new combination, Muhlenbergia alopecuroides (Griseb.) P. M. Peterson & Columbus, is made based on published and ongoing molecular phylogenetic studies.

The dwarf mistletoes (Arceuthobium spp., Viscaceae) are an ecologically and economically important group of hemi-parasitic flowering plants that parasitize members of the Pinaceae in both the Old and New Worlds. There are two areas of maximum diversity for the dwarf mistletoes: northern California and Durango, Mexico. Here we provide additional information on the distribution of dwarf mistletoes in Durango based on field observations and herbarium collections. This information supplements data provided in a monograph on Arceuthobium published in 1996. Needed research on the dwarf mistletoes in Durango is also discussed. Key words: Arceuthobium, distribution, dwarf mistletoes, Durango, México.

Two new roses are described from California and adjacent Oregon, with keys to distinguish each from the typical representative of their respective species. Rosa pisocarpa A. Gray subsp. ahartii Ertter & W. H. Lewis differs from typical R. pisocarpa by generally having fewer and larger leaflets, fewer flowers, and sepals that are most commonly eglandular, among other features. It is the characteristic member of the R. blanda Aiton complex in the northern Sierra Nevada and southern Cascade Range, where existing collections have been variously identified as R. pisocarpa, R. woodsii Lindl. subsp. ultramontana (S. Watson) Roy L. Taylor & MacBryde, R. californica Cham. & Schltdl., and R. bridgesii Crépin ex Rydb. The rank of subspecies is used to indicate a significant ecogeographic component of the species' range. In contrast, varietal rank is used for a localized expression of R. gymnocarpa Nutt. occurring on open ultramafic substrates in northwestern California and adjacent Oregon, described here as Rosa gymnocarpa var. serpentina Ertter & W. H. Lewis. Diagnostic characters include relatively short stature, fewer and blunter leaflets, and pedicels that are frequently eglandular.