Antennaria howellii subsp. gaspensis comb, et stat. nov. (Asteraceae : Inuleae): justification for change

Canonical discriminant analysis was used to assess the taxonomic status of Antennaria neodioica Greene var. gaspensis Fernald. Results based on these analyses indicate that Antennaria howellii Greene, Antennaria microphylla Rydberg, A. neodioica var. gaspensis, Antennaria pulvinata Greene, and Antennaria rosea Greene are morphologically distinct. High cross-validation assignment rates as well as high Geisser assignment probabilities for each of the taxa support this statement. Elevating var. gaspensis to the rank of species is in part supported by the data analysis, but doing so would be contrary to the species standard method and inconsistent with recent practice in revisions of the genus. The presence of scarious appendages at the tips of the upper cauline leaves, the open pedicellate inflorescence, the whitish-green capitula, general growth form, agamospermous reproduction, chromosome number, provenance, and quantitative morphology, in addition to the results of the canonical discriminant analysis, support recognition of var. gaspensis at an infraspecific rank. In keeping with the criteria utilized in recent revisions of the genus, var. gaspensis should more appropriately be treated as a subspecies. Recent nomenclatural rearrangements in A. neodioica and A. howellii founded on the priority of the latter lead to the following new combination: Antennaria howellii subsp. gaspensis (Fernald) Chmielewski. Key words: Antennaria howellii var. gaspensis, Asteraceae, Newfoundland flora, Gaspé Bay Peninsula flora.

Allelopathy of Small Everlasting (Antennaria microphylla): Identification of Constituents Phytotoxic to Leafy Spurge (Euphorbia esula)

The ether extract of small everlasting (Antennaria microphyllaRydb.) was phytotoxic to lettuce seed root growth and leafy spurge (Euphorbia esulaL. # EPHES) root elongation and cell culture growth. Three phenolic compounds (hydroquinone, arbutin, and caffeic acid) were chromatographically isolated and characterized from the ether extract. Arbutin and caffeic acid were moderately phytotoxic to leafy spurge root growth at 300 ppm (w/v), and hydroquinone was strongly phytotoxic to leafy spurge root growth at 50 ppm (w/v). The observed phytotoxicity of hydroquinone and the high-yield natural occurrence of arbutin, a water soluble, easily hydrolyzed monoglucoside of hydroquinone, in small everlasting is consistent with the participation of these two compounds in the observed allelopathy of small everlasting against leafy spurge.

Triploidy in the genus Antennaria (Asteraceae: Inuleae)

Chromosome numbers for individuals from 87 populations of Antennaria from western Canada were counted. Naturally occurring triploid (2n = 42) hybrid populations between diploid (2n = 28) Antennaria microphylla Rydb. and two tetraploid (2n = 56) species Antennaria rosea Greene and Antennaria umbrinella Rydb. are reported for the first time. With the discovery of the triploid populations, an entire euploid series (2x–8x) has been established for the genus Antennaria.Key words: polyploidy, Antennaria, hybridization, agamospermy, taxonomy.

The Antibiotic Effects of Plants in Laboratory and Field

In laboratory experiments, plant extracts of small everlasting (Antennaria microphylla Rydb.), field pussytoes (A. neglecta Greene), and leafy spurge (Euphorbia esula L.) were toxic to germinating seeds. Extracts of small everlasting inhibited vegetative development of leafy spurge, and soil taken from the immediate vicinity of roots inhibited germination and radicle elongation of germinating seeds of some species. Small everlasting competes vigorously with leafy spurge, and this competition cannot be attributed to morphology and growth habit. It suppressed vegetative growth of leafy spurge from rhizome sections in which the two species were competing in pots. In field experiments, this shallow-rooted, lowgrowing plant exhibited a marked inhibition on the growth of the vigorous, deep-rooted perennial, leafy spurge, as did the soil in which small everlasting had been growing. Antibiotic competition appears to be significant with the Antennaria spp., and the paucity of forbs in patches of leafy spurge, even when bare ground is visible between shoots, suggests that this species also exerts antibiotic effects on other plants. Allelopathy is probably a significant influence in interspacial relationships of species in most plant communities. A fuller knowledge of these relationships and their causes could lead to the utilization of this phenomenon in weed control.