Cold, Rain, and Buttercups

We have had welcome rains, and apparently we should expect more around the time that this column appears. That’s good, but that weather prompts some salient observations.

First, although the drought has been broken for the present, we should regard the present period as a hiatus, rather than an end to dry times. Long-term projections still indicate below average rainfall in future years,

Most importantly, our aquifers were depleted significantly during the drought years, and replenishing them will require many years of at least normal rainfall. We will have to wait for encouraging reports on that front.

Meanwhile, examine your garden for possible negative impacts from the recent cold and rainy days. The plants in my garden are nearly all native to California or other summer-dry (Mediterranean) climates, so they managed well during the dry days.

One exception was a mature Chilean Myrtle (Luma apiculata) that succumbed to the drought, and had to be removed.

That experience recalls a thoughtful comment by Alexander Graham Bell: “When one door closes, another opens; but we often look so long and so regretfully upon the closed door that we do not see the one which has opened for us.” In this case, the tree had grown larger than expected and closer to the house than wanted, so while I regretted its loss, its absence opened space for new plants.

Almost all my succulent plants shrugged off the cold spell, with the exception of a Foxtail Agave (Agave attenuata), which I had been growing in a large container. I planned to plant it in the ground eventually, to provide the space it will need to reach its full size of four feet high and eight feet wide. The plant’s rosette is quite attractive and dramatic, but its distinctiveness is based on its flower stalk, which grows five-to-ten feet, reflexes to the ground and then arches upward again. I learned too late that this plant is unusual among Mexican native succulents for its susceptibility to cold weather. I should have covered it, or brought it inside. It lost some leaves, but now appears to be coming back.

I have been taking advantage of the fine weather between rainstorms by catching up (with help!) on the seasonal weeding tasks. This work includes the annual battle with Bermuda buttercup (Oxalis pes-caprae), a South African native that thrives in California’s coastal gardens, and opens its bright yellow blossoms in late winter or early spring.

Bermuda Buttercups

Bermuda Buttercups

I have been puzzled by the relentless and random spread of this annoying plant. The explanation on UC’s Integrated Pest Management website (ipm.ucanr.edu/) has been incomplete:

“Viable seed never has been documented in California, and rarely has it been seen anywhere else in world. Foliage dies and the bulbs become dormant when temperatures rise in late spring and summer. Bermuda buttercup reproduces vegetatively by bulbs and spreads when plants are divided or soil containing the bulbs is moved to un-infested areas.”

I have learned that this plant is tristylous, an uncommon morphology meaning that it has three flower shapes (morphs). All the flowers on a given plant will have the same shape, but the pollen from a flower on one morph cannot fertilize another flower of the same morph.

Tristyly does not necessarily affect the propagation of the Bermuda buttercup, but it might explain its spread in gardens, and provide a clue to its management. The search goes on!

Meanwhile, we continue with weeding and mulching, and preparing to enjoy the garden in the spring.

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