Roadside Revegetation

IMPLEMENTATION GUIDES
rough cleaned” seed ratios (Table 10-12) can help calculate the extra weight of seeds to collect
in the wild to compensate for seed cleaning. Dividing the desired amount of cleaned seeds
by this ratio will yield the amount of wild seed that needs to be collected.
Determine Seed Needs for Seedling Production
The quantity of wild seeds to collect for propagating seedlings at plant nurseries will be based
on an estimate of (1) quantity of seedlings needed, (2) percent seed germination, (3) percent
seed purity, (4) seeds per pound, and (5) nursery factor. An estimate of germination, purity,
and seeds per pound can be obtained through published sources, seed inventories, or from
seed extractory managers. The nursery factor is a prediction of the percentage of viable seeds
that will actually become “shippable” seedlings. Each nursery has developed a set of factors
based on culturing experience and practices. Nursery managers should supply nursery factors
for each species or information on the amount of seeds to collect to meet the seedling order.
Nursery factors are often less than 50 percent.
Using the following equation, the amount of wild seed to collect can be estimated:
Wild seed to collect =
quantity of seedlings needed
(% germ/100 * % purity/100 * seeds/pound * nursery factor/100)
Locate Plants in the Wild
Figure 10-51 | Wild collected
seed needs to be cleaned
Field collected seeds include stems,
chaff, flower parts, and seed attachments.
Species such as cutleaf silverpuffs
(Microseris laciniata) have a low “cleanto-rough”
seed ratio and must be sent
to a seed extractory for cleaning prior
to sending to seed producers.
Collection areas are located in the field during the vegetation analysis phase (see Section
6.2, Select Species for Propagation). General collection locations can be established by the
revegetation specialist under the direction of a botanist familiar with the local vegetation.
Contracts often require seed collectors to identify individual collection areas for approval
prior to collection. Since seed collection can start in late spring for some species, collection
site location must be completed by this time.
Collection areas for each species should not occur in one location, but represent a crosssection
of populations in the general area of the project. A minimum of five collection areas,
at least a mile apart, should be identified for each species. This ensures that a range of genetic
characteristics is represented in each seedlot. While some populations will be located in
the project area, most areas will have to be found in adjacent areas. When seed collection
Table 10.12 | Typical ranges of “cleaned-to-rough cleaned” seed ratios
To obtain the amounts of “rough” seeds to collect, divide the amount of cleaned seeds needed by the “cleaned-to-rough cleaned” ratio. For
example, if 5 lb cleaned seeds of prairie Junegrass (Koeleria macrantha) are needed, a minimum of 12.5 lb rough cleaned seeds must be collected
(5/40*100=12.5) (Chart based on R6 Forest Service seed collections data.)
Common Name Scientific name Cleaned-to-Rough Cleaned Ratio
Bluebunch Wheatgrass Pseudoroegneria spicata 25 to 33
Idaho Fescue Festuca idahoensis 33 to 50
Prairie Junegrass Koelaria macrantha 20 to 40
Squirreltail Elymus elymoides 20 to 25
Yarrow Achillea spp. 20 to 25
Sandberg Bluegrass Poa secunda 33 to 40
Blue Wildrye Elymus glaucus 50 to 65
Roadside Revegetation: An Integrated Approach to Establishing Native Plants and Pollinator Habitat
284