Phenological Patterns in the Desert Spring Ephemeral Astragalus holmgreniorum Barneby (Fabaceae)

Rominger, Kody R.; Meyer, Susan E.; Buren, Renée Van; Searle, Allyson B.

doi:10.3398/064.079.0303

Cited by 5 publications

(9 citation statements)

References 26 publications

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“…In sand-deserts of central to eastern Iran, Growth of A. squarrosus started in late February and was followed by reproduction in early April to late July, summer dormancy in late July to early October, vegetative regrowth from early October to late November and winter dormancy from late November to late February (Batoli, 2008). Rominger et al (2019) reported the same phenology of A. holmgreniorum in the Mojave Desert (USA) in which the life cycle is a perennial spring ephemeral with dormancy during summer, autumn and winter. Temperatures higher than 30 o C induce summer dormancy in this species.…”

Section: )mentioning

confidence: 78%

“…The life cycle of Astragalus starts with germination of seeds in autumn (Ralphs et al, 2003;Martínez-Sánchez et al, 2011;Han et al, 2018), autumnearly winter (Meinke et al, 2009), winter (Pavlik & Barbour, 1988;Han et al, 2018), early spring (Sankary & Barbour, 1980;Baskin & Baskin, 1989b;Fotheringham & Keeley, 1998;Ralphs et al, 2003;Kondo & Takeuchi, 2004;Rominger et al, 2019) or autumn and spring (Beatley, 1970;Looman, 1974;Maschinski et al, 1997). Germination time is mostly related to the timing of rainfall in arid and semi-arid climates.…”

Section: Life Cycle and Life Formmentioning

confidence: 99%

“…For example, the blooming period was late May to mid-June for A. flexuosus and A. striatus at 1580-1680 m elevation but late June to early July at 2367 m. The blooming period for A. alpinus at 2380-3080 m ranged from mid-June to mid-August. The flowering peak of A. holmgreniorum was early April in the Mojave Desert, regardless of weather variation (Rominger et al, 2019). Some Astragalus species have two periods of dormancy: during the cold winter and during the hot, dry summer.…”

Section: )mentioning

confidence: 99%

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Reproductive biology, ecological life history/demography and genetic diversity of the megagenus Astragalus (Fabaceae, Papilionoideae)

et al. 2021

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Astragalus is the largest genus of seed plants; however, information on its reproductive biology and life history is widely scattered in the literature. About 96% of the species are perennials and 4% annuals; many are rare endemics. Astragalus species are obligate or facultative outcrossers, and inbreeding depression is higher in self-compatible (SC) than in self-incompatible (SI) species. The most frequent pollinators are Bombus, Osmia and Anthophora. On average, 48% of ovules produce seeds, and 40% of flowers produce fruits. Seed/ovule and fruit/flower ratios are lower in SC than in SI species. Predispersal insect seed predation ranges from 0 to 93%, and major predators are Acanthoscelides, Bruchophagus and Tychius. Seeds have physical dormancy and typically form a seed bank. C 3 is the only photosynthetic pathway in the genus. Population growth may be cyclic or noncyclic, and genetic diversity of a taxon may or may not be related to size of geographic range.

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Section: )mentioning

confidence: 78%

Section: Life Cycle and Life Formmentioning

confidence: 99%

Section: )mentioning

confidence: 99%

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Reproductive biology, ecological life history/demography and genetic diversity of the megagenus Astragalus (Fabaceae, Papilionoideae)

et al. 2021

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“…and Wildlife Service, 2006). The species is a spring ephemeral hemicryptophyte, with dormant meristems very close to the soil surface (Rominger et al, 2019). Initiation of shoot growth takes place in early February, flowering and seed production occur from March to mid-May, and by mid-June all aboveground vegetative tissue has senesced.…”

Section: Study Speciesmentioning

confidence: 99%

“…Hygrochasy functions in many species as a mechanism for timing seed release during germination-triggering rain events (Gutterman, 1990(Gutterman, , 1994Martínez-Berdeja et al, 2014). This is not likely to be the case for A. holmgreniorum because its seeds are physically dormant and not germinable at dispersal (Searle, 2011;Rominger et al, 2019). Instead, when the fruit itself functions as a diaspore, as in A. holmgreniorum, hygrochasy and subsequent washing out of the seeds can act to curtail maladaptive within-pod dispersal.…”

Section: Hygrochasy As a Mechanism To Time Seed Release Prevent Dispersal And Reduce Predationmentioning

confidence: 99%

Pods as sails but not as boats: dispersal ecology of a habitat‐restricted desert milkvetch

Houghton

Stevens

Meyer

2020

American J of Botany

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Adaptive seed dispersal mechanisms are fundamental to plant fitness, but dispersal advantage is scale-dependent. We tested the hypothesis that informed dispersal in response to an environmental cue enables dispersal by wind on a local scale for Astragalus holmgreniorum, a desert species restricted to swales and wash skirts with overland flow, but prevents longer-distance dispersal by water into unfavorable wash habitats.METHODS: Pod biomechanics in A. holmgreniorum lead to major shape modifications with changes in moisture content. We performed laboratory experiments to examine the interaction of pod shape with wind and water, and conducted field experiments in A. holmgreniorum habitat evaluating the roles of wind, water, and seed predators on dispersal.RESULTS: Dry pods exhibit a flattened crescent shape with partial dehiscence that facilitated wind dispersal by ground tumbling and seed scattering in laboratory experiments. Rain simulation experiments showed that even small precipitation events returned wetted pods to their cylindrical shape and opened the dorsal suture, exposing the seeds. In the field experiments, dry pods were moved locally by wind, whereas rain caused pod opening and washing out of seeds in place. Seed predators had minimal effect on pod movement. CONCLUSIONS:Astragalus holmgreniorum exhibits pod structural remodeling in response to environmental change in a striking and novel demonstration of informed dispersal. Winddriven movement of dry pods facilitates local seed dispersal, but rain causes pods to open and release seeds, ensuring that they are not transported out of suitable habitats and into active washes where they would be lost from the seed bank.

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Life‐history strategy and extinction risk in the warm desert perennial spring ephemeral Astragalus holmgreniorum (Fabaceae)

Buren

Searle

Meyer

2021

Ecology and Evolution

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This study of Astragalus holmgreniorum examines its adaptations to the warm desert environment and whether these adaptations will enable it to persist. Its spring ephemeral hemicryptophyte life‐history strategy is unusual in warm deserts. We used data from a 22‐year demographic study supplemented with reproductive output, seed bank, and germinant survival studies to examine the population dynamics of this species using discrete‐time stochastic matrix modeling. The model showed that A. holmgreniorum is likely to persist in the warm desert in spite of high dormant‐season mortality. It relies on a stochastically varying environment with high inter‐annual variation in precipitation for persistence, but without a long‐lived seed bank, environmental stochasticity confers no advantage. Episodic high reproductive output and frequent seedling recruitment along with a persistent seed bank are adaptations that facilitate its survival. These adaptations place its life‐history strategy further along the spectrum from “slower” to “faster” relative to other perennial spring ephemerals. The extinction risk for small populations is relatively high even though mean λs > 1 because of the high variance in year quality. This risk is also strongly dependent on seed bank starting values, creating a moving window of extinction risk that varies with population size through time. Astragalus holmgreniorum life‐history strategy combines the perennial spring ephemeral life form with features more characteristic of desert annuals. These adaptations permit persistence in the warm desert environment. A promising conclusion is that new populations of this endangered species can likely be established through direct seeding.

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Phenological Patterns in the Desert Spring Ephemeral Astragalus holmgreniorum Barneby (Fabaceae)

Cited by 5 publications

References 26 publications

Reproductive biology, ecological life history/demography and genetic diversity of the megagenus Astragalus (Fabaceae, Papilionoideae)

Reproductive biology, ecological life history/demography and genetic diversity of the megagenus Astragalus (Fabaceae, Papilionoideae)

Pods as sails but not as boats: dispersal ecology of a habitat‐restricted desert milkvetch

Life‐history strategy and extinction risk in the warm desert perennial spring ephemeral Astragalus holmgreniorum (Fabaceae)

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