The year that we collected seed for this study was unfortunately part of a prolonged drought. Collection was difficult because some species from which we wanted to collect seed did not grow at all, were hard to find, or did not produce seed. Another problem was heavy predation by insects and wildlife. These facts should be kept in mind when using the data below.
After we collected seed, we cleaned it to the point necessary for hand broadcast seeding. We then weighed the bulk amount of each species that we had. To translate this into number of seeds, we took five small subsamples from each species. For each subsample, we weighed the bulk amount, and then separated out the ripe, filled, undamaged seed. We counted these good seeds to give us an idea of the number of seeds per unit mass of material that we would hand broadcast in our experimental plots. For some species we also weighed these clean seeds for information on individual seed mass.
To access information on an individual species, go to the species table.
Definitions/explanations of each of the terms used in the species seed collection information are below.
Average number of good seeds per gram bulk matter: Average number of seeds per gram of bulk matter, as measured in five subsamples. Number in parentheses following average is standard deviation.
Average number of good seeds per gram cleaned: Average number of seeds per gram of pure seed, separated from chaff, stems, leaves, etc., from five subsamples. Note that this is not necessarily PLS (pure live seed), as we do not have information on seed viability for many species. Number in parentheses following average is standard deviation.
Commercial estimates of seeds per gram: Values come from a variety of sources, including Natural Resource Conservation Service technical guides, commercial catalogs, and National Park Service native species propagation documents. Keep in mind that these values are for very clean seed compared to what we were measuring (e.g., awns from needle grasses removed).
Percent seed: pure seed mass/bulk seed mass X 100%, where pure seed mass is the weight (in grams) of the good seed, free of chaff, stems, etc. from a subsample, and bulk seed mass is the weight (in grams) of the seed matter cleaned to the state of planting by hand broadcast seeding (usually includes chaff, some small leaves, etc.).
Percent live: percent of seed that was viable, as measured by South Dakota State University Seed Laboratory.
Collection dates: Dates that we collected seed at Wind Cave National Park, southwestern South Dakota, foothills of the Black Hills, in 2004. Many species matured late this year because of a late spurt of moisture after dry conditions early in the summer.
Collection effort: A very rough estimation of how much time it took to collect the given mass of bulk seed for a species. Estimates are rough because we often were collecting many species at the same time.
"n.m." means not measured; "n.a." means not available
Achillea millefolium – common yarrow
Amorpha canescens – leadplant
Andropogon gerardii – big bluestem
Anemone cylindrica – candle anemone, thimbleweed
Aristida purpurea – red three awn
Artemisia frigida – fringed sagewort
Artemisia ludoviciana – white sage, man sage
Asclepias speciosa – showy milkweed
Bouteloua curtipendula - sideoats grama
Bouteloua gracilis – blue grama
Bouteloua hirsuta – hairy grama
Brickellia eupatorioides – false boneset
Calylophus serrulatus – yellow evening primrose
Cirsium undulatum – wavyleaf thistle
Dalea purpurea – purple prairie clover
Dyssodia papposa – fetid marigold
Echinacea angustifolia – purple coneflower
Elymus elymoides – squirreltail bottlebrush
Erysimum asperum – western wallflower
Gaura coccinea – scarlet gaura
Glycyrrhiza lepidota – wild licorice
Grindelia squarrosa – curlycup gumweed
Gutierrezia sarothrae – broom snakeweed
Helianthus annuus – common sunflower
Hesperostipa comata – needle and thread
Heterotheca villosa – hairy false golden aster
Ipomoea leptophylla – bush morningglory
Koeleria macrantha – prairie junegrass
Liatris punctata – dotted gayfeather
Lithospermum incisum – narrowleaf gromwell
Monarda fistulosa – bee balm, horse mint
Nassella viridula – green needlegrass
Oligoneuron rigidum – stiff goldenrod
Onosmodium molle – false gromwell
Pascopyrum smithii – western wheatgrass
Penstemon grandiflorus – large beardtongue
Plantago patagonica – wooly plantain
Psoralidium tenuiflorum – slimflower scurfpea
Ratibida columnifera – prairie coneflower
Rosa arkansana – prairie wild rose
Schizachyrium scoparium – little bluestem
Solidago missouriensis – prairie goldenrod
Solidago nemoralis – gray goldenrod
Sporobolus cryptandrus – sand dropseed
Symphoricarpos occidentalis – western snowberry
Symphyotrichum ericoides – heath aster
Verbena bracteata – prostrate vervain
Verbena stricta – hoary vervain
