Golden Gate Gardener

Pokeweed--A huge and Toxic Weed

In my SF Chronicle Column for November, I reported on a weed that has been sighted in San Francisco. It's a native in the  Eastern part of the U.S., so I was surprised to find it here, but there it is. I also saw one down the Peninsula this summer, though I forget just where. 

The plant is large, 4-10 feet tall, and most parts and stages of it are toxic to most mammals. I described it in my column, but was unable to get a photo of it into the print version. However, I can show a photo here. This is an image of a stem of berries. Botanists call this kind of flower or fruit-bearing stem a raceme. The berries are dark purple. When they are ripe, their stems and the longer central stem of the raceme are usually bright pink. The stems of ripe berries are the most recognizable parts of the plant. 

Photo by Andra Sadoun

You may find it surprising, given the toxicity of this plant, to know that it has long been a part of the diet of rural people in the South and eastern-central parts of the U.S.one of the young greens gathered and eaten in spring.  Only the leaves of very young plants are eaten, and they must be boiled two or three times, with the boiling water drained off of them between boilings and after the last one. This dish is called "poke sallet." (It important to know that the word "sallet" derives from an old English word that meant cooked greens, not salad, as the raw leaves would be toxic.)

The berries are toxic, and eating only a few has killed small children. Though some say the seeds are the most toxic part, it hardly seems worth the risk to try them. Birds seem immune to the berry toxin, so the fruit is eaten by many kinds of birds, including Northern mockingbird, mourning doves, and cedar waxwings. Raccoons and possums may also be able to eat the berries, though most mammals cannot.

The most toxic part of all is the root. The plant is perennial, likely to regrow from last year's roots, so the best way to get rid of it is to dig it out. Wear gloves, as the toxin can enter through skin. Then pick up any fallen berries you see, and watch for seedlings. (The young plants are sort of nondescript, with large oval, pointed leaves.)

How did the weed get here? Presumably from bird-planted seed, but it's possible the seed was assisted by some other form of transportation. It could have stowed away in tire treads or shoe treads. While there are domestic varieties, are grown as ornamentals, their leaves look different from the wild plant. (The ornamental varieties are  ‘Silberstein’, which has pale, cream-colored leaves with green spots, and ‘Sunny Side Up’, with yellow-green leaves.) The ones being found in the Bay Area seem to have normally green leaves, meaning are not escaped ornamentals.

 

Spring Bloom in Fall--It's a Problem

In today's SF Chronicle (January 1, 1917), I wrote about plants that bloomed last fall in San Francisco that ought not to have been blooming until spring, caused by continuing climate change.

While it's true that we typically have our warmest "summer" weather from mid-September to mid-October, this weather has been lasting longer than usual. Last fall, the warm days and mild nights lasted until near the end of November. We celebrated time spent outdoors in nice weather, but some of our garden plants reacted by blooming and leafing out as if it were spring. This is a problem for the plants, which put energy and physical matter into doing this, so that when spring really does come, they have less stored matter and food energy to do it all again. This weakens the plant, leaving it more susceptible to all kinds of setbacks.

Case in point is my apple tree, which has borne bountiful crops of delicious apples for 30 years. But recently it has been trying to bloom in fall. Then, because winters aren't quite cold enough, it blooms later than usual in the spring. And, because of the energy it used up in fall, it blooms more sparsely. Two years ago, it had practically no fruit.

Last year it did better, though not as well as it used to do. The photo below, which I sent to the Chronicle, but they didn't use in the paper, shows my tree last November, with a few last apples and last leaves till hanging on while blooms and new leaves opened all around them. Now, on January 1, all the new leaves have succumbed to cold, wasting all that effort.

If you are growing other temperate plants in the Bay Area, such as cherries and plums (ornamental or fruiting), magnolias, lilacs, or azaleas, you may be having the same kind of problem. What's to be done to save our plants? Obviously continue to work against climate change, a movement in which California in general is doing well.  But we can also join an effort to record the changes, in which our regional data will provide extremely valuable evidence.

More data about how climate change is affecting plants in our region is especially important so that we are represented in a system that has so much more data from cold-winter regions.

There are two organizations that are seeking citizen science data. One is the National Phenology Network (www.usapn.org/), sponsor of the National Phenology Project. It studies both plant and animal species. Another, Project Budburst (budburst.org), is studying only plant responses. Phenology is the study of what plants and animals do in response to seasonal changes.

Sending records to these databases is easy to do online. Log in, choose a plant, and tell them what it is doing on various dates. Children can do it at home and school classes can do it. Both web sites have curriculum information to help teachers fit the work into classes. It teaches observation, appreciation of plants, climate science, ecology, and how science is done

So as our new, and rather unnerving, year begins, please help observe and record what is going on with nature. Your reports will be powerful.

Some Resources for Waterwise Gardeners

This is not meant to be a complete list, by any means, but here are a few publications and links that will be useful if you are selecting plants for a waterwise garden.

WUCOLS stands for Water Use Classification of Landscape Plants. This project, sponsored by UCDavis, California Dept of Water Resources, California Center for Urban Horticulture, lets you find out the water needs of over 3,500 landscape plants in six different regions of California. The most recent version WUCOLS IV,can be accessed at the following address:

http://ucanr.edu/sites/WUCOLS/   Click on "Plant Search" Or you can use this link: WUCOLS IV

For information on growing California Native Plants, check out the Las Pilitas web site, laspilitas.com, or use this link: Las Pilitas Nursery.

Here are links to two articles on the subject of watering trees during a drought that were recently in the San Francisco Chronicle:

Trees Out on A Limb

Watering Trees in A Drought

Finally, here is a short list of books that you will find useful as you seek ideas and plants for a waterwise garden:

California Native Plants for the Garden, Burnstein, Fross, O'Brien, Cachuma Press, 2005.Photos, text on garden uses and care.

New Sunset Western Garden Book. I think the most recent is 2012, and it does have all color photos, which are helpful, but the text of couple of editions right before this one were a little more thorough.

Plant Life in the World's Mediterranean Climates, Peter B. Dallman, University of California Press, 1998. Maps and charts show how the 5 mediterranean regions are similar and, importantly, how they differ, then explains the habitats to which many of our favorite plants are adapted.

 Plants and Landscapes for Summer-dry Climates of the San Francisco Bay Region, East Bay MUD, 2004. Inspiring photos and useful information.

The Random House Book of Indoor and Greenhouse Plants, Roger Phillips & Martyn Rix, Volumes 1 & 2, Random House,1997. Despite the name, thiese two volumes cover mostly mediterranean and other subtropical plants that we can grow outside. The photos and text about the plants in their native habitats are very useful.

Wildly Successful Plants: Northern California, Pam Peirce, Sasquatch Books, 2004.California garden history, plant origins, garden maintenance instructions, garden design, and a philosophy for a regional garden.

A Tree Story and a New Salad Crop

First a story about my apple tree. When we moved in it was a sad little tree, pruned so badly that it wasn't bearing any apples. Now, over 20 years later, it is a fine-looking tree, with many apples every year. But recently it has had some problems with scab, rosy apple aphid, and with the dread woolly apple aphid, a pest that lives in the roots as well as on the branches.

  So I was digging out the soil around the tree, since one thing I wanted to try is to dig just to expose the top roots and then pour diluted horticultural oil over the soil and water it in. (The oil I use is made from canola oil, and I diluted it as if for a spray, so the drench is mostly water.) In any case, I was digging away while my friend Lisa, who is an arborist, was doing a little pruning, when I suddenly stopped and called her over. Here is what I saw. The trunk had no roots for the first foot or so, and then I came to the place where the trunk flared out a little bit. This is where the soil should have been all along! It is clear that the people who sold us the house had piled soil aroung the trunk, burying it. This is very bad for a tree, and may have made it more susceptible to the pest that has been bothering it. Look at the right side of the base of the trunk for that little bit of flare. That's the bottom. If you look closely, you can see the change of color on the trunk, from the dirty, previously buried part to the cleaner, not ever buried part. It is right at the top of the last wet streak. Mind you, other arborists have looked at this tree and not noticed. Lisa had said "That trunk bothers me. It doesn't have much flare." Boy was she right!

So I kept on digging. It looks like someone just dumped a bunch of soil at the bottom of the garden, ignoring the tree. Not a good idea. Gardeners out there: Don't bury the trunk of your trees. Not even a little bit. That trunk base needs air, and you will at best make the tree susuceptilble to diseases and pests, or, at worst, kill the tree.

As I dug, I suddenly saw what I should have seen years ago, but didn't: The bottom stair leading down to the tree was also buried. Look at that! The top one is normal height, but the bottom one is very shallow. I have been excavating since this photo and we have had to haul out some of this extra soil. When I get it down to the right level, I will add some mulch, but not right up against the trunk, since that would also limit its ability to breath. I'm glad my soil is kind of high in sand. If it had been clay, I might have a dead apple tree at this point!

Meanwhile, in the vegetable garden, I've been trying out some new "greens." This one, as you can see, is really red, or purple. It is the same species as the big purple-leaved, spicy mustard that is rather common. But this little plant is only about 8 inches tall, and is rather mild. It is called 'Ruby Streaks'. Territorial Seeds has it as does Nichols Garden Nursery and Johhny's Select Seeds. There is a lime green version as well. So far, the purple one has grown faster in the cold spring and has a milder flavor than the green one. But both are really striking in a salad. I think they'd be pest harvested at 4-5 inches long for that purpose. Both "streaks" are growing faster than the mizuna mustard we planted. It's a different species, Brassica rapa, while the "streaks" are B. juncea.

And, just because it's spring, here are some daffodils I shot last week. Happy spring!