Native Iowa Understory Woodland Restoration: A Guide to Collecting and Germinating Seeds

GERMINATION METHODS

Most woodland herbaceous species demonstrate higher germination after a period of cold, moist stratification (see below). Germination may occur during stratification (like with Arisaema triphyllum or Smilacina racemosa) or after stratification. If germination has been observed for a species during stratification, it is noted in the propagation notes. Qualitative comments on seedling survivorship were gathered primarily from greenhouse observations following transfer of seeds or seedlings from the stratification container to a greenhouse flat with soil. Survival notes from field observations are included where available.

• Cold, moist stratification. Cold, moist stratification is accomplished by mixing seed with damp sphagnum and storing the mixture in a closed container (like a plastic, cottage cheese tub) in a refrigerator. The mixture should be inspected periodically for fungal growth, which can result in rapid seed deterioration. Most species require about 3 months of cold stratification.
  
  
• Cold, dry stratification. Cold storage over the winter may be all that is necessary for some species prior to planting in the spring. Species that are intolerant of dry storage are noted as such.
  
  
• Intolerant of artificial stratification. Spring ephemerals, particularly those with eliaosomes, are usually intolerant of any type of long-term storage or artificial stratification. Most lose viability when the seed dries out, and others require a period of warm stratification to ensure proper embryo development. Consequently, seed should be sown at a restoration site as soon as possible after collection.

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