Both Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) and red alder (Alnus ruba Bong) use seeds as a method of reproduction. Gymnosperms, such as Douglas-fir, have “naked” seeds (i.e. no fruit), while angiosperms, such as red alder, usually have seeds in fruit (catkins for red alder). Douglas-fir and red alder have seeds that use wings, signifying the use of the wind as a method of seed dispersal. Both trees have seeds than are covered in a seed coat and have nutrient reserves. Gymnosperms, however, have a large megagametophye, which is the haploid nutritional tissue. Angiosperms typically have a smaller megagametophye, that later develops into an endosperm (red alder, however, does not have an endosperm). When seeds germinate, general 4 steps usually occur first:
1) Imbibition, when seeds swells with water and the seed coat ruptures
2) Metabolism increases. Cell division starts and radicales elongate and emerges
3) Hormones from the embryo initiate enzymatic activity to hydrolyze stored food reserves
4) Cotyledons and/or plumules are pushed above the soil surface
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It is positively gravitropic, while the shoot is negatively gravitropic. Root hairs are then later developed from the radicale. Both Douglas-fir and red alder have epigeous germination (cotyledons pushed out of ground). Mycorrhizal fungi could appear in Douglas-fir lateral roots, while red alder has nitrogen fixing nodules form. Both species’ habitat are primarily in the Pacific Northwest. Douglas-fir is a climax species, living for long periods of time, and appearing in old-growth forests. Red alder is typically a pioneering species, distributing large number of seeds and have a fast growth