Camas and Micro-seasonality at Minto-Brown Park

We all are aware of the annual seasons, winter, spring, summer, and fall, but in the growing cycle of the plants of the Willamette Valley there are micro-seasons when specific plants rise and expend their energies. (there is probably a botanical term for micro-seasons but not sure what that is.) This is the case at Minto-Brown park, during the first spring micro-season, with few flowers and plants just beginning to grow. For Camas, in about March-April, they sprout their long leaves and it takes some weeks for the central flower to begin to rise.


May 4th 2022, note leaves are fully grown out and central stalk rising with tight cluster of pre-flowers

There are a few early plants that rise but the majority are just waking from hibernation. Then the next micro-season has the majority of plants with their central stalk rising and the bottom layer of flowers opening. In May most camas of whatever variety are up and either opening flowers and then turning into green seed pods.

Giant camas with flowers opening from the bottom first, 6/4/2022

Then in June the camas are nearly all exhausted and turning into green seed pods, drying up to brown. Except for some fields, which for whatever reason (to be determined) some fields have camas rising in June. I have noticed that the common camas are seeding in June, while the more robust giant camas are still rising and many have yet to fully flower.

June 4 2022, green seed pods

The Camas flower opens in stages, working up from the bottom layer of flowers, and over the course of several weeks the flowers at each layer open until after a month the top layer is in flower. Common camas tend to have less flower layers and less density of flowers about the central stalk. The giant camas has a pronounced central stalk with a tightly bound cluster of unopened flowers.

Common camas, late May, note less density of flowers and there is not a pronounced top knot


Note the pronounced and tightly clustered top knot of the giant camas, notice also the height of the grass next to the tallest giant camas.

For all April to the beginning of June, Camas is the major flower in the prairies where it still exists, sometimes in dense growth which appears to be like a large purple-blue sea. But in June the grasses rise and begin to dominate the prairies, drowning the camas under brown and tan grass stalks. Then we see a few other flowering plants rise and become dominant, The mallows, like common mallow begin to take over fields where it is prominent. At this time tarweed begins to rise, not yet flowering, and right behind it, thistle is rising, which will ultimately become dominant.  The grass and Tarweed micro-season will take over the fields from the earlier camas micro-season. By July all camas should be in seed and drying up to become a rattle. Tarweed flowers will dominate even in the tall grasses.

The tall grasses have now outgrown the common camas, 6 4 2022


These micro-seasons are fascinating. In the WV camas dominates the early season, then tarweed will come along to dominate the prairies. By the end of the tarweed season, in September, camas will have fully retreated into the bulbs underground, the seeds easily dispersed from their rattling dry shells. It would have been at this point that the tribes would burn the prairies, roasting and [preparing tarweed seeds for gathering, clearing off excess dead growth, and stressing undesirable plants like thistles.

Tarweed (large green leaves) now rising, common camas in background 6 4 2022
Layers, Camas (flowering and seeding), and grasses on top, common mallow center, then thistle at the ground. 6 4 2022

For Minto-Brown- there is no fire season, and the City of Salem has yet to adopt cultural fire management, they normally mow the fields. This is an artificial human-made condition because it would be normal to have a fire there at regular intervals.  It would be interesting to see if the return of fire management to Minto-Brown would stress the thistle and blackberries and other undesirable to the point where they become less intrusive. The native plants, camas, tarweed, and mallows, are adapted to fire management after thousands of years of cultural fires set by Kalapuyans, so they will survive fine and perhaps thrive better. Interestingly Minto-Brown is perfectly situated for cultural fire, without much housing crowding the park and with much of the park overgrown with invasives, blackberries, English ivy, and now scotch broom coming back. Mowing does nothing to control invasives and may in fact help them by eliminating or interrupting the seasons of native plants.

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