Northern Prairie Wildlife Research Center
=
155, df = 5, P < 0.001). The regression showed there was a strong tendency among
species for length of the blooming period to increase as the growing season
progressed (F2,80 = 8.38, P = 0.0005). However,
date of first flowering accounted for only about 17% of the variation in blooming
period. Our analysis of similar data presented by Budd and Campbell (1959) gave
almost identical results (F2,107= 7.89, P
= 0.0009). We suspect that one of the reasons for this increase is that many
of the earliest- blooming species are small and adapted to set seed quickly
before being shaded by taller plants later in the growing season. The flowering
periods for plants such as dandelion (Taraxacum officinale, a perennial)
and goatsbeard (Tragopogon dubius, a biennial) in the native and seeded
grasslands we studied are much shorter than those measured by Budd and Campbell
(1959). We attribute these differences to the lack of cultivation and heavy
grazing on our study area. At least for dandelion, shading by dense vegetation
seems to stop the flowering process (C. Godfread, pers. commun.).
| Table 1. Flowering dates and periods for 97 species of upland and wet-meadow plants near Woodworth, North Dakota, arranged according to earliest first flowering date, 1979-1984. | ||||||
| Species | Flowering datesa | Length of flowering period (days) | ||||
| Earliest first bloom | Latest first bloom | Median date of first 10 plants with flowers | Median date of full flowering | Median date when flowering 95% complete | ||
| Anemone patens | 3/22/81 | 4/30/79 | 4/16 (5) | 4/20 (6) | 5/01 (5) | 15 |
| Lomatium orientale | 3/30/81 | 5/8/79 | 5/02 (4) | 5/06 (5) | 5/16 (5) | 14 |
| Phlox hoodii | 4/10/81 | 5/16/79 | 5/02 (5) | 5/05 (5) | 5/23 (5) | 21 |
| Taraxacum officinale | 4/13/81 | 5/23/79 | 4/22 (5) | 5/16 (5) | 5/28 (4) | 36 |
| Potentilla concinna | 4/24/80 | 5/20/79 | 5/09 (4) | 5/16 (5) | 5/28 (5) | 19 |
| Ranunculus rhomboideus | 4/24/80 | 5/14/79 | 4/29 (4) | 5/04 (4) | 5/21 (4) | 22 |
| Thlaspi arvense | 4/24/81 | 5/23/79 | 5/14 (4) | 5/25 (4) | 6/11 (3) | 28 |
| Draba nemorosa | 4/25/80 | 5/21/79 | 5/04 (4) | 5/10 (5) | 5/20 (4) | 16 |
| Viola nuttallii | 4/25/80 | 5/23/79 | 5/14 (3) | 5/14 (5) | 6/02 (5) | 19 |
| Oxytropis lambertii | 4/26/81 | 5/23/79 | 5/05 (5) | 5/17 (5) | 6/04 (5) | 29 |
| Cerastium arvense | 4/29/81 | 5/29/79 | 5/18 (5) | 5/22 (5) | 6/12 (4) | 25 |
| Astragalus crassicarpus | 5/01/80 | 5/30/79 | 5/19 (4) | 5/21 (6) | 6/01 (4) | 13 |
| Lithospermum canescens | 5/04/81 | 5/29/79 | 5/18 (5) | 5/23 (6) | 6/17 (6) | 30 |
| Lesquerella ludoviciana | 5/04/81 | 5/21/79 | 5/11 (4) | 5/16 (5) | 5/29 (5) | 18 |
| Crataegus chrysocarpa | 5/05/81 | 5/31/83 | 5/20 (4) | 5/24 (4) | 6/05 (4) | 16 |
| Hierochloe odorata | 5/06/80 | 5/23/84 | 5/16 (3) | 5/23 (5) | -- | -- |
| Comandra umbellata | 5/09/80 | 6/7/79 | 5/26 (4) | 6/05 (4) | 6/26 (5) | 31 |
| Geum triflorum | 5/10/83 | 6/6/79 | 5/13 (4) | 5/22 (5) | 6/19 (6) | 37 |
| Amelanchier alnifolia | 5/10/82 | 5/30/79 | 5/11 (4) | 5/17 (4) | 5/28 (4) | 17 |
| Zizia aptera | 5/12/80 | 6/1/82 | 5/28 (5) | 6/05 (5) | 7/09 (5) | 42 |
| Prunus virginiana | 5/12/80 | 6/2/83 | 5/25 (5) | 6/01 (5) | 6/09 (5) | 15 |
| Allium textile | 5/12/81 | 5/29/79 | 5/23 (5) | 5/28 (4) | 6/05 (2) | 13 |
| Ribes americanum | 5/12/80 | 6/6/79 | 5/18 (4) | 5/21 (3) | 6/09/(2) | 22 |
| Viola pedatifida | 5/13/81 | 5/31/79 | 5/18 (4) | 5/21 (3) | -- | -- |
| Poa pratensis | 5/13/81 | 6/11/79 | 5/21 (5) | 6/03 (5) | -- | -- |
| Potentilla anserina | 5/16/81 | 6/19/83 | 5/27 (5) | 6/01 (3) | 7/03 (3) | 37 |
| Castilleja sessiliflora | 5/18/81 | 6/13/79 | 6/02 (4) | 6/09 (3) | -- | -- |
| Elaeagnus commutata | 5/19/80 | 6/13/79 | 6/02 (6) | 6/04 (6) | 6/19 (6) | 17 |
| Lithospermum incisum | 5/20/84 | 5/30/79 | 5/23 (4) | 5/28 (4) | 6/11 (3) | 19 |
| Agoseris glauca | 5/21/81 | 6/13/79 | 5/29 (5) | 6/05 (5) | 6/18 (5) | 20 |
| Sisyrinchium angustifolium | 5/22/80 | 6/12/79 | 6/03 (5) | 6/05 (5) | 6/25 (5) | 22 |
| Vicia americana | 5/23/84 | 6/6/79 | 5/31 (3) | 6/04 (5) | 7/01 (3) | 31 |
| Anemone canadensis | 5/27/80 | 6/15/79 | 6/04 (5) | 6/16 (5) | 7/09 (5) | 35 |
| Bromus inernis | 5/27/80 | 6/13/79 | 6/07 (6) | 6/24 (6) | -- | -- |
| Penstemon albidus | 5/28/82 | 6/13/79 | 5/30 (5) | 6/08 (5) | 6/30 (5) | 31 |
| Melilotus officinalis | 5/28/80 | 6/25/79 | 6/14 (6) | 6/23 (6) | 7/28 (3) | 44 |
| Calylophus serrulatus | 5/28/80 | 6/25/79 | 6/22 (4) | 6/28 (4) | 7/27 (4) | 35 |
| Tragopogon dubius | 5/29/80 | 6/17/82 | 6/10 (6) | 6/20 (6) | 7/03 (6) | 23 |
| Silene cserei | 5/29/80 | 6/27/79 | 6/15 (4) | 6/21 (5) | 7/02 (3) | 17 |
| Rosa woodsii | 5/29/80 | 6/25/79 | 6/14 (6) | 6/22 (6) | 7/05 (6) | 21 |
| Rosa arkansana | 5/29/80 | 6/26/82 | 6/28 (6) | 6/29 (6) | 7/31 (6) | 33 |
| Gaura coccinea | 5/29/80 | 6/26/82 | 6/19 (5) | 6/26 (5) | 7/09 (3) | 20 |
| Galium boreale | 5/29/80 | 6/21/79 | 6/11 (6) | 6/19 (6) | 7/11 (6) | 30 |
| Polygala alba | 5/29/80 | 6/26/79 | 6/12 (4) | 6/20 (5) | 7/30 (4) | 48 |
| Koeleria pyramidata | 5/29/80 | 6/27/79 | 6/11 (6) | 6/19 (4) | -- | -- |
| Stipa viridula | 5/30/80 | 6/24/79 | 6/15 (6) | 6/24 (6) | -- | -- |
| Asclepias ovalifolia | 5/30/80 | 6/27/79 | 6/20 (4) | 6/26 (4) | 7/31 (3) | 41 |
| Stipa comata | 5/30/80 | 6/21/79 | 6/13 (5) | 6/24 (5) | -- | -- |
| Gaillardia aristata | 5/30/80 | 6/23/79 | 6/11 (5) | 6/20 (5) | 7/12 (4) | 31 |
| Medicago sativa | 5/30/80 | 6/21/83 | 6/16 (6) | 7/01 (6) | 8/11 (4) | 56 |
| Erigeron philadelphicus | 5/31/84 | 6/26/79 | 6/02 (4) | 6/11 (4) | 6/29 (3) | 27 |
| Psoralea esculenta | 6/01/80 | 6/21/79 | 6/11 (5) | 6/18 (5) | 7/05 (4) | 24 |
| Campanula rotundifolia | 6/04/80 | 6/25/79 | 6/21 (6) | 7/01 (6) | 8/01 (5) | 41 |
| Agropyron repens | 6/04/80 | 6/19/83 | 6/17 (4) | 6/29 (2) | -- | -- |
| Stipa spartea | 6/06/80 | 6/25/79 | 6/25 (5) | 7/08 (5) | -- | -- |
| Sphaeralcea coccinea | 6/07/80 | 7/7/83 | 6/15 (4) | 6/29 (4) | 7/10 (3) | 25 |
| Apocynum cannabinum | 6/08/80 | 7/10/79 | 6/30 (4) | 7/07 (4) | 8/10 (3) | 41 |
| Apocynum androsaemifolium | 6/09/80 | 6/21/83 | 6/20 (3) | 6/29 (4) | 7/22 (3) | 32 |
| Achillea millefolium | 6/11/80 | 6/25/79 | 6/21 (6) | 6/25 (6) | 8/01 (6) | 41 |
| Glycyrrhiza lepidota | 6/11/80 | 7/9/79 | 7/07 (6) | 7/15 (6) | 7/31 (6) | 24 |
| Onosmodium molle | 6/13/80 | 7/16/79 | 6/19 (4) | 6/26 (5) | 7/15 (3) | 26 |
| Zigadenus elegans | 6/13/80 | 6/27/79 | 6/22 (4) | 6/30 (5) | 7/17 (5) | 25 |
| Symphoricarpos occidentalis | 6/13/80 | 7/10/79 | 6/25 (6) | 7/06 (6) | 7/28 (6) | 33 |
| Penstemon gracilis | 6/17/80 | 6/26/84 | 6/22 (4) | 6/26 (5) | 7/10 (3) | 18 |
| Psoralea argophylla | 6/17/80 | 7/13/79 | 7/07 (6) | 7/15 (6) | 8/02 (6) | 26 |
| Dalea candida | 6/17/80 | 7/8/82 | 7/05 (3) | 7/14 (5) | 8/03 (5) | 29 |
| Dalea purpurea | 6/17/80 | 7/13/79 | 7/11 (5) | 7/15 (5) | 8/15 (4) | 35 |
| Lilium philadelphicum | 6/17/80 | 7/3/79 | 6/27 (6) | 7/08 (6) | 7/16 (6) | 19 |
| Ratibida columnifera | 6/17/80 | 7/13/79 | 7/06 (4) | 7/14 (6) | 8/16 (5) | 41 |
| Stachys palustris | 6/18/80 | 7/10/79 | 6/30 (4) | 7/11 (4) | 8/09 (2) | 40 |
| Echinacea angustifolia | 6/20/80 | 7/12/79 | 7/06 (6) | 7/11 (6) | 8/02 (6) | 27 |
| Amorpha canescens | 6/23/80 | 8/4/79 | 7/17 (5) | 7/24 (5) | 8/12 (5) | 26 |
| Lobelia spicata | 6/23/80 | 7/10/83 | 7/05 (5) | 7/12 (5) | 8/02 (4) | 28 |
| Rudbeckia hirta | 6/23/80 | 7/12/79 | 7/08 (5) | 7/15 (5) | 8/15 (4) | 38 |
| Anemone cylindrica | 6/23/80 | 7/16/79 | 7/02 (5) | 7/07 (5) | 7/26 (5) | 24 |
| Chrysopsis villosa | 6/24/80 | 7/10/84 | 6/30 (5) | 7/22 (5) | 8/31 (4) | 62 |
| Bouteloua gracilis | 6/25/80 | 7/18/79 | 7/09 (6) | 7/29 (2) | -- | -- |
| Panicum virgatum | 6/27/80 | 7/21/83 | 7/17 (3) | 7/26 (3) | -- | -- |
| Cirsium arvense | 6/30/82 | 7/12/83 | 7/08 (5) | 7/19 (4) | 8/10 (4) | 33 |
| Lactuca oblongifolia | 7/03/84 | 7/7/81 | 7/05 (3) | 7/13 (3) | 8/18 (3) | 44 |
| Liatris punctata | 7/07/80 | 7/31/82 | 7/26 (5) | 8/05 (5) | 9/02 (4) | 38 |
| Solidago missouriensis | 7/07/80 | 7/20/79 | 7/15 (5) | 8/01 (5) | 8/27 (4) | 43 |
| Andropogon gerardii | 7/07/80 | 8/3/79 | 7/18 (4) | 8/06 (4) | -- | -- |
| Aster ericoides | 7/07/80 | 8/15/79 | 8/11 (4) | 8/24 (5) | 9/07 (4) | 27 |
| Gutierrezia sarothrae | 7/08/80 | 8/15/79 | 7/26 (4) | 8/05 (5) | 9/04 (4) | 40 |
| Solidago canadensis | 7/09/81 | 8/3/79 | 7/30 (4) | 8/08 (5) | 9/11 (5) | 43 |
| Liatris ligulistylis | 7/09/80 | 8/3/79 | 7/26 (5) | 8/05 (5) | 8/28 (4) | 33 |
| Cirsium flodmanii | 7/10/80 | 8/3/83 | 7/19 (4) | 7/26 (5) | 8/28 (4) | 40 |
| Allium stellatum | 7/14/80 | 7/25/84 | 7/19 (3) | 7/30 (5) | 8/23 (3) | 35 |
| Grindelia squarrosa | 7/14/80 | 7/26/84 | 7/25 (4) | 8/08 (3) | 9/04 (3) | 41 |
| Helianthus rigidus | 7/21/82 | 8/1/79 | 7/25 (5) | 8/05 (5) | 8/30 (4) | 36 |
| Helianthus maximiliani | 7/22/83 | 8/2/81 | 7/25 (6) | 8/09 (6) | 9/01 (5) | 38 |
| Orthocarpus luteus | 7/24/79 | 8/2/83 | 7/29 (2) | 8/03 (5) | 8/27 (3) | 29 |
| Gentiana affinis | 7/25/80 | 8/10/81 | 8/08 (3) | 8/09 (2) | 8/17 (2) | 9 |
| Solidago rigida | 8/01/82 | 8/3/79 | 8/03 (4) | 8/10 (4) | 9/02 (4) | 30 |
| Prenanthes racemosa | 8/03/82 | 8/31/79 | 8/14 (4) | 8/20 (5) | 8/31 (3) | 17 |
| Gentiana andrewsii | 8/16/81 | 8/24/83 | 8/19 (3) | 8/23 (4) | 9/13 (3) | 25 |
| a
Figures in parentheses indicate number of years for which records
were available. b Length of flowering period calculated as the interval in days between median dates of the first 10 plants with flowers and flowering 95% complete. |
||||||
Climatic conditions differed greatly among periods (year- month combinations) when large numbers of plants initiated flowering early versus when they initiated flowering late (Table 2). The greatest proportions of spring and early- summer plants bloomed early during March-April 1981, May 1980, and June 1980. Although departures from normal precipitation were small during these periods, the periods were warmer than the corresponding periods during the other four years of the study. Except for July-August, precipitation at Woodworth was actually slightly less during periods when we observed most early blooms than when we recorded most late blooms. The relation between within-period climatic conditions and early blooming did not hold for the mid-summer species, i.e. those for which we recorded earliest flowering during July-August. Indeed, cooler temperatures and increased precipitation characterized July-August 1980, the period when the largest number of mid-summer species bloomed early. It is likely that earliest flowering records for this period were a response to the two earlier periods in 1980 which were markedly warmer than average.
In summary, temperature seems much more important than precipitation in influencing phenology of prairie plants in central North Dakota. Spring flowering is probably stimulated more by warm temperatures than by heavy precipitation. A combination of warm temperatures and ample moisture in late summer seems to extend the blooming period.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://www.npwrc.usgs.gov/resource/plants/flwrdate/results.htm
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