California oatgrass is unique in the way it reproduces because it contains two different types of seeds, cleistogamous and chasmogamic seeds. The presence of each of these seeds is very important in determining their life cycles. For instance, cleistogamous seeds are formed from a closed flower because they self-pollinate (Darris and Gonzalves 2008). However, open flowers cross-pollinate which results in the production of chasmogamic seeds which are known to have higher levels of germination since they reproduce more quickly (Darris and Gonzalves 2008). Cleistogamy, or self-fertilization of a closed flower, requires fewer plant resources, which can be beneficial when the plant becomes attacked or damaged. The flowering of California oatgrass occurs between the months of May and July when the temperatures are warmer, but don’t expect to see flowering within the first year of growth. This organism develops very slowly, so the second and third years are more common for the initial site of flowering (Darris and Gonzalves 2008). Once California oatgrass begins to flower, those flowers produce pollen. Unlike most other flowering plants, grasses do not require insects to spread the pollen. Instead, California oatgrass is anemophilous, or wind-pollinators. The pollen grains in these seeds are transported by wind.

General view of California oatgrass with permissionGermination of this organism depends on many factors. First off, dormancy can be very common in California oatgrass. An organism in dormancy refers to the length of time that growth and development is interrupted. Even if they are dormant in the ground, seeds in this plant can still germinate. It has been shown that these seeds can germinate more quickly if they are scattered and watered promptly (Darris and Gonzalves 2008). Storage of the seeds at different temperatures, overpopulation, aggressive seed conditioning, and restricted gas exchange (Darris and Gonzalves 2008) are all things that play a role in California oatgrass being dormant. Temperatures too low or too high can cause a seed to be dormant, as well as overpopulation of organisms within the same general area. The use of machines to plant the seeds can also decrease the chance of them germinating (Darris and Gonzalves 2008); seed dispersal should occur naturally. On the other hand, dormancy can be beneficial when trying to maintain overpopulated areas by mowing (Wilson and Clark 2001), grazing and burning (Hatch et al. 1999), and herbicides (Darris and Gonzalves 2008). The picture above shows an unidentified Danthonia, but is a good example of how compact these grasses can be and still thrive in their environment. In 2001, Wilson and Clark  performed an experiment to show how mowing grasses at certain lengths can affect the growth rates of those grasses. This type of experiment was also constructed by Hatch and his colleagues in 1999 by using burning methods, and also Darris and Gonzalves in 2008 with the use of herbicides. More details of these experiments can be found on the Adaptation page. Other organisms such as the California Harvester ant and the Pacific Shrew may use California oatgrass seeds as a source for food, which is another benefit to maintaining this organism so it does not overpopulate.

A unique aspect of California oatgrass is that some seeds require light to germinate, while others do not (Darris and Gonzalves 2008) though it is not determined which type of seeds (cleistogamous or chasmogamous) require a light source. This organism is also a host for the Gloeotinia temulenta, a fungus that many other native grasses host as well.

Stem of California oatgrass with permission

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