The Pollination Ecology of Astragalus cibarius and Astragalus utahensis (Leguminosae)

Green, Thomas W.; Bohart, George E.

doi:10.2307/2442091

Cited by 18 publications

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“…olympicus flowers at Blue Mountain and Mount Angeles. These are typical pollinators of rare and common species of Astragalus (Green and Bohart, 1975;Karron, 1987) and other alpine legumes (Shaw and Taylor, 1986). They were capable of tripping the floral mechanism and were relatively faithful to A. australis var.…”

Section: Discussionmentioning

confidence: 99%

“…Stebbins (1957) asserts that rare plants are likely to be self-compatible. This may be true for Astragalus, where some common species are self-incompatible (Green and Bohart, 1975) and their rare congeners set selfed seed freely (Karron, 1989). Inbreeding depression in seedlings was not tested in A. australis var.…”

Section: Discussionmentioning

confidence: 99%

“…No effort was made to quantify pollinator efficiency. Instead, to establish the presence of potential pollinators, the identity and ability of insect visitors to work the legume floral mechanism (Green and Bohart, 1975;Faegri and van der Pijl, 1979) were observed.…”

Section: Pollination-a Pollinator-exclusion Experimentsmentioning

confidence: 99%

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From flowering to dispersal: reproductive ecology of an endemic plant, Astragalus australis var. olympicus (Fabaceae)

Kaye

1999

American J of Botany

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Astragalus australis var. olympicus is an endemic plant of the Olympic Mountains, Washington. It is considered a Species of Concern by the U.S. Fish and Wildlife Service. This study focused on the reproductive biology of the plant from flower production through seed germination to identify possible weak points that might contribute to its rarity and impede its conservation. Most plants produced a large mean number of flowers and ovules (314.8 and 4106, respectively), but relatively few of these formed fruits and seeds (25.8 and 3.8%, respectively). In decreasing importance, ovules in fruits were lost to predation, seed abortion, and lack of fertilization. The percentages of these fates differed among sites and years. Excluding pollinators by bagging flowers reduced fruit set by ∼50%, but seed set per fruit and seed mass were unaffected. Germination was affected by scarification, temperature, and moisture availability. About 11% of seeds damaged by predispersal seed predators (weevil larvae) remained viable and were released from dormancy. I hypothesize that predispersal seed predation (over 80% at one site) has a negative effect on population growth. Conservation of this species could benefit from improved fruit set and decreased seed predation.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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From flowering to dispersal: reproductive ecology of an endemic plant, Astragalus australis var. olympicus (Fabaceae)

Kaye

1999

American J of Botany

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“…Hence the sympatric legumes, D. hispida, D. uncinata and P. densifolia present similar but unique images and rewards to fforal visitors. Among sympatric plant species, where bees are the major pollinators, small differences in floral morphology (Green & Bohart 1975;Jones 1978) can influence pollinator fidelity. Furthermore, since bees are particularly sensitive to UV (Daumer 1956in Kevan 1973, variation among sympatric species within the UV wavelengths represents a potentially significant difference.…”

Section: Discussionmentioning

confidence: 99%

Floral traits and pollinator constancy: Foraging by native bees among three sympatric legumes

Gross

1992

Australian Journal of Ecology

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The foraging constancy of the solitary bee, Trichocolletes sp., was documented in a semi-arid ecosystem where three morphologically similar legumes co-occur. To quantify the degree of tloral similarity among the forage plants, Dillwynia hispida, Dillwynia uncinata and Pultenaea densifolia, discriminant function analysis of petal dimensions and a spectral analysis of corolla colour was undertaken. Petal si/e varied moderately among species resulting in 2-14% of specimens being misclassified, usually asD. uncinata. Subtle variation in corolla colour in the ultraviolet wavelengths contributed to the distinctiveness of each species. All three species exhibit an UV-absorbing region at the base of the standard petal which contrasts sharply with the rest of the UV-retlecting petal. Between 450 nm and 470 nm, per cent reflectance drops for D. hispida and P. densifolia, but remains steady for D. uncinata. Above 480 nm, parts of the standard petal in all species reflect similar amounts of light with little variation exhibited among species. Nectar was only otfered by D. hispida and D. uncinata, whereas P. densifolia produced an excess of pollen which may serve as a reward. Despite the subtle differences in tloral morphology and rewards among these sympatric legumes, Trichocolletes bees only remained faithful to a given species in 43"'i) of 183 interplant flights. Inconstant foraging by Trichocolletes sp. increases the pool of resources because rewards in all three legume species can be obtained in exactly the same manner.

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“…Interactions between plants and pollinators have stimulated much interest, particularly where co-occurring plant species overlap in flowering phenology, fioral characters and floral visitors (e.g. Green & Bohart 1975;Macior 1975;Jones 1978;Waser 1978a,b;Hannan 1981;Schemske 1981;Rathcke 1983;Waser & Price 1983;Macior 1983;Armbruster & Herzig 1984;Campbell & Motten 1985;Stucky 1985;Karron 1987). When several species utilise the same inconstant pollinators, plant fitness may potentially be (i) elevated, (ii) lowered or (iii) unaffected.…”

Section: Introductionmentioning

confidence: 99%

Is resource overlap disadvantageous to three sympatric legumes?

Gross¹

1996

Australian Journal of Ecology

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The sympatric legumes Dillwynia hispida, Dillwynia uncinata and Puhenaea denstfolia overlap in flowering phenology, floral characters and native bee pollinators. Tests for pollenlimitation were conducted to determine whether or not the overlap in pollinator use was detrimental to individuals of these species. Polien limitation was only detected in D. hispida. Pollen loads on bees were examined and it was found that pollen loads from Dillwynia and P. densifoUa were spatially segregated on the pollinator's body reducing the likelihood of pollen transfer between these species. The polien of D. hispida and D. uncinata overlapped on the heads of bees suggesting that interspecific pollinations may be responsible for lowered fruit-set in D. hispida. However, hand pollinations involving heterospecific pollen and controlled floral visits by bees to the two Dillwynia species revealed that heterospecific pollen loads did not significantly depress fruit-set in either D. hispida or D. uncinata. Pollinator preferences were examined in detail and it was found that D. uncinata flowers received twice as many bees in a day compared with D. hispida and P. densifoUa. Competition through pollinator preference is implicated here as a mechanism of competition. Intraspecific competition is also implicated as D. hispida was pollen limited in the absence of D. uncinata and P. densifoUa.

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The Pollination Ecology of Astragalus cibarius and Astragalus utahensis (Leguminosae)

Cited by 18 publications

References 0 publications

From flowering to dispersal: reproductive ecology of an endemic plant, Astragalus australis var. olympicus (Fabaceae)

From flowering to dispersal: reproductive ecology of an endemic plant, Astragalus australis var. olympicus (Fabaceae)

Floral traits and pollinator constancy: Foraging by native bees among three sympatric legumes

Is resource overlap disadvantageous to three sympatric legumes?

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