A Shower of Stars

Monarch butterflies are exceptionally rare in western Washington, but if you're going to see one, June is the most likely month for them to be on this side of the Cascades. Their breeding ground is centralized in the Columbia Basin, but occasionally, an ambitious or misguided individual may cross the mountains. However, milkweed is also scarce here, and it is the host for Monarch caterpillars. I wouldn't want a little Monarch caterpillar to go hungry, so I've put some milkweed in the Barren Wasteland "just in case." I'd also like to have some dried pods for crafting, but although insects succeeded in pollinating a few of the flowers last year (where my own attempts failed), the pods rotted on the plants when our customary wet fall weather arrived. For the record, milkweed has a lovely sweet scent. I can understand the Monarchs' attraction to it, but I have yet to see one.

Milkweed Dehiscence

Day 42: After weeks of waiting patiently for my milkweed pods to dehisc, only to see them developing mold in our damp weather, I decided it was time for an intervention. I cut the stems and laid them inside the unheated garage where I hoped they would dry and split. I wasn't even sure they'd ripened, since they had never turned brown as I felt they should have done, left alone on the plants. Now it has to be said that I don't generally have much reason to go in the garage, so they were there for a week or two before I opened the door again. That brief disturbance of the air as the door swung back sent milkweed fluffies into every nook and cranny in the building! They drifted down like snowflakes as my mind struggled to comprehend what was happening, so unexpected was the sight. You know what they say: Be careful what you wish for. Dehiscence had indeed occurred. In spades.

Pod Growth

Day 314: When something dries out, it shrinks. That's an inescapable fact. And logically, the more water it has to lose, the rate of shrinkage will be different. Obviously, a cherry tomato would shrink more than a similarly-sized walnut meat simply because it has a higher water content. Nevertheless, having seen dried milkweed pods, I was not expecting fresh ones to be quite so enormous! These are already four inches long. Taking a tangential detour in the discourse here, and having come face-to-face with my own mortality at my annual checkup, I have to wonder if the next owner of this property will appreciate the inheritance of botanical diversity my garden supports: milkweed, Akebia, kiwi vines, gooseberries, a medlar tree, and hiding under leaves, a treasured stick which sprouts aqua-blue fungus with the arrival of autumnal humidity.

Podlings

Day 300: The milkweed pods are coming right along! I have two areas each supporting half a dozen plants, seed for which came from two different sources. The second area is a year or two younger, and I am fairly sure that group is only going to produce one pod this year. However, the older group may have as many as two dozen. I haven't really taken a count. Once a blossom has been pollinated, the pedicel (the stem of an individual flower in an inflorescence) begins to thicken and curl. Then the ovary starts to swell into a pod which will eventually dehisc (remember your botany vocabulary from a few days ago!) to release dozens of seeds, each attached to a silky pappus. The pappus (a parachute-like structure) aids in wind dispersal of the seeds...and trust me, when you open an envelope of them inside your kitchen without knowing what's inside, "wind dispersal" can apply to the gentle breeze conjured by the slightest physical motion on the part of the unsuspecting recipient. I will be confining these in net bags before they dehisc so that they don't populate the neighbourhood. I am truly excited to have grown my own milkweed pods at last!

We Have Pollination!

Day 291: We have pollination! Yes, my milkweed plants are making pods! And I cannot credit the success to my intervention because the flower I attempted to pollinate by hand is not among those with swelling ovaries. That said, there are at least a dozen strikingly obvious developing pods on the plants which flowered earliest, and I think there will also be some on the plants which came into bloom a little later. It's too soon to tell with those, although it looks like a few of the flower stems are beginning to curl (as opposed to drooping). That was what caught my eye first: one curled, plump flower stem held above a mass of withering flowers. Closer examination revealed an ovary starting to swell, and then as I raised my eyes, I saw this pod, about as big as the end of my thumb! Then I really started peering in among the fading flower clusters, and saw that the pollinators had done the job I'd failed to do. Finally, I'm going to have milkweed pods!

Bee Hopeful

Day 281: I have good reason to "bee hopeful" that my milkweed plants will produce seed pods this year. They are absolutely covered with a large assortment of insects...stinging insects, mind you!...who visit one flower after another. Bees dominate the mix, but there are wasps of every size from miniscule to man-eating, so I stood well back and zoomed in for the photo. Can I identify them? No, although I think I can safely say that these two are honeybees, a species to which I am deadly allergic. Was I worried that I would get stung? Not at all, because they were firmly focused on the work at hand, gathering nectar from the sweet-scented flowers. Surely sombody's going to get pollinia caught on a leg!

Milkweed Reproduction

Day 272: The first phase of this project consisted of learning to identify the reproductive structures of Asclepias syriaca, Common Milkweed. You'd think that milkweeds kept the family jewels in the same place as other plants do, but as it turns out, the flower is rather different in that it centers on a gynostegium (new word for me!), which is comprised of fused stigmas and stamens. What lay people would call the "flower" (the white part, in this case) is the corona. It consists of hoods and horns (five each). The petals of the flower depend beneath it. Between hoods, a careful observer will note a swollen brownish bump at the inner end of the stigmatic slit (see center image). This is the corpusculum. It is essentially the "bear trap" in which an insect's leg can become ensnared. Attached to the corpusculum are two pollinia, sticky agglomerations of pollen. In the instance of A. syriaca (or at least those in my garden), the corpusculum and attached pollinia measured something in the neighbourhood of half a millimeter long. I was able to tease two "units" out using the microscope and a dissecting needle, but once on the tray, I could barely see them with my naked eye. Nevertheless, "sticky" was the operative word. They gummed themselves to the tip of the dissecting needle nicely, and I was able to transport them to the garden. As to whether or not I successfully poked them into the stigmatic slit of a second plant remains to be seen. I had no way to magnify the flower while keeping both hands free to perform the cross-pollination. There was an unexpected bonus to this experiment: I discovered that milkweed is deliciously fragrant as I stood there with my beak in the blossom, pretending I was a bug.

Milkweed in Flower

Day 271: The milkweed is blooming! The plants bore only a few flowers last year, and while I had hoped that an appropriate pollinator would stop by, no pods ever developed. There will be more opportunity this year, though, because there are many more flowers on plants in two patches. Surely some innocent bug will get a leg trapped long enough to pick up some pollinia. That's how milkweed works. Pollen transfer occurs in sticky packets, not dry grains. A bug's leg gets caught inside a slit in the stigma, wiggles around as the insect tries to free itself, and the sticky pollen packets (which generally occur in pairs) get tangled in the hairs on its leg. The insect then visits another milkweed flower, makes a similar mis-step, gets trapped again, and in its efforts to free itself, the pollinia comes off inside the stigma of the second plant. And it has to be a different plant. Milkweed is not self-fertile. Sidebar: I have seen a video of a botanist attempting to cross-pollinate a rare milkweed. Gives me ideas, that, and I'm sure by now, you know that I enjoy botanical match-making. Anybody thinking there might be an experiment on the horizon? Worth a try, but I might not be able to tell who was the responsible party, me or a bug. Not exactly a controlled experiment, but if I get milkweed pods, I'd be happy. Tweezers...where'd I put the dissecting tweezers?

Milkweed At Last!

Day 281: At last! The Milkweed (Asclepias syriaca) has a few open flowers! This stem is the only one out of a dozen or so which carries an inflorescence (two, actually), but considering that it has taken three or four years to reach this point, I have hopes that at least some of the others will follow suit next year. As for the types of pollinators it may attract, I'm not expecting Monarchs. They are quite uncommon in western Washington, and I have never seen one. However, I'm sure they're not the only butterfly which finds Asclepias appealing. I can't imagine having to hand-pollinate the flowers, but I'll keep my little paintbrush handy because I want to grow these for the pods. I'll be watching for insect activity, although I haven't seen many butterflies of any species in the yard yet this year.