Tuesday, October 27, 2015

Botanizing in Alaska: Claytoniella bostockii

I've previously posted about a couple of plants from a shattered-rock slope we encountered outside of Fairbanks (the-biologist-is-in.blogspot.com/2015/07/botanizing-in-alaska-dwarf-birch.html; the-biologist-is-in.blogspot.com/2015/07/botanizing-in-alaska-mountain-avens.html). Though I had taken a break from posts about the biology I encountered on my Alaska trip, there remain still several to go from this site alone.

This particular plant was Marie's favorite. I was eventually able to identify it as Claytoniella bostockii, a plant in the Purslane family (Portulacea). It is a native plant to the area, but doesn't seem to have any common names in English.

It appears to grow perennially, regenerating from roots every year. There were many small plants in addition to ones as large as seen in the second photo, which presumably took several years to grow. I'm certain there are biologically interesting things about this plant, but I didn't spend any real time examining the actual plants so I can't add to the paltry amount of information available online. Maybe on the next trip, I'll take better notes.


Tuesday, October 20, 2015

Violet Surprise 2

Earlier in the season I found a violet with fringed leaves growing in an overgrown garden (the-biologist-is-in.blogspot.com/2015/05/violet-surprise.html). There are a few violet species which typically have similar fringed leaves (V. triloba, V. palmata, & V. pedata), but it is pretty clear that the plant I found doesn't represent any of these species. I identified the plant as being a novel mutant form of the Viola sororia (Common Blue Violet) that is growing all over the yard.

Earlier in the summer, we performed an accidental experiment involving lots of hosta plants. Most of them were green and a few were variegated. The deer immediately started eating the green hostas, with such vigor that they pulled some of the plants out of the ground. The variegated hostas remained untouched... for a while, at least. The result of this experiment is that the deer are hesitant to eat something that looks different from what they're used to.

I realized that violets are also considered delectable to deer when I planted some other violet plants into a garden bed and watched them repeatedly get nibbled to the ground. I find myself wondering if the survival of this fringed plant before I found it was due to its novel look. It could also be that the plant was just hiding better. Compared to the typical violet, the fringed leaves made this plant better camoflaged among the grasses and such which were growing around it.

Either way, I like the look of the plant and am hoping to propagate it further. V. sororia creeps along the ground, growing new branches while older sections of stem die with age. Over time a single plant will become many vegetative clones spread over a wider area. This is a slow method of propagating a violet, but fortunately the biology of violets provides a faster method.

Early in the growing season, a violet plant produces the stereotypical purple/violet flowers. In the heat of summer, flower production falls off. Once cooler weather arrives with fall, flowering starts up again. However, these flowers are different than the spring flowers. These flowers never open their petals and develop on very short stems, so remaining hidden at the base of the plant. Because they never reveal their reproductive parts, they're referred to as cleistogamous flowers. The flowers pollinate themselves and then develop more obvious seed pods. Once the seeds are mature, the seed pod rotates to point upwards and the seeds are forcefully ejected by the drying of the fruit sections.

A simple way to save the seeds is to wrap the pods in a simple loop of cellophane tape. The tape will remain attached to the pod as it ripens and rotates. When the fruit sections dry out, the seeds are forcefully ejected onto the sticky tape (as in the image at right) where they remain for collection.

If the parent plant is highly inbred, the seeds collected from a cleistogamous flower will represent near clones of the parent. Because of this feature, the seeds I'm collecting from the mutant V. sororia will likely grow to also have the interesting fringed leaves. (All Viola species share this pattern of flowering, including pansies.)


Tuesday, October 13, 2015

The Gall of Those Goldenrods

S. canadensis flowers.
Goldenrods (genus Solidago) are blooming prolifically in southern Minnesota. This patch is near the building I work at, but I find them blooming in parks, along roads, and in my own yard. Though they are considered weedy and potentially invasive, I like the look of the flowers and they make an interesting subject for study due to the various animal species which interact with it.

One of the more studied interactions is between the Goldenrod and the Goldenrod Gall Fly (Eurosta solidaginis). This fly causes the Goldenrod to grow hard bulbous galls in the main stem that are referred to as "ball galls". The galls are easy to collect during winter, so ample material is available for teaching or research purposes.
S. canadensis flower galls.

Though I have found a few of the ball galls, the Goldenrod patch near my work didn't seem to have any. The patch was full of another type of gall, however. These galls are formed at the top of the stem and look like a tight cluster of leaves, forming a flower-like head structure. Because of the appearance, they are referred to as "bunch galls", "rosette galls", or "flower galls".

Goldenrod flower gall.
If you take one of these flower galls and dissect it carefully, it has an internal structure very similar in organization to the flower of a sunflower plant. There is a broad flat disk with leafy structures (florets or leaves), on top of a pithy core which widens as it approaches the base. Ok, I admit it is a bit of a stretch, but there is enough similarity to have the name "flower gall" make some sense.

When I first saw these galls, I had assumed they were caused by an infection with a fungus that was using the flower-like structure to trick insects into carrying its spores to other plants. (Check out the Cedar Apple Rust gall for an example of a fungal "flower" used for spore dispersal.)

R. solidaginis larva.
When I cut open the Goldenrod flower gall, I found several small insect larvae. They had no identifying markers, aside from their characteristic flower gall. After doing a bit of research, I found these were larva of the Goldenrod Gall Midge (Rhopalomyia solidaginis). These small flies are parasites of a specific Goldenrod species, Solidago canadensis.

I've had limited success finding information about the life-cycle of the Goldenrod Gall Midge. The few references I've found which talk about the insects' life cycle refers to two life-cycles per year. The larva I found represent the summer juveniles, which will pupate into fall adults. These fall adults will lay eggs in the ground (or the base of the Goldenrod plants?), which then quickly hatch and overwinter as larvae. These larvae would then grow quickly and pupate in spring to make the later generation of adults to infect the Goldenrods and produce the flower galls. I've known that the life-cycles of parasites often include multiple hosts or stages of growth, but I didn't realize this one was going through its complicated life right under my nose in the wild-flower patch.


Tuesday, October 6, 2015

Wild Capsicum annuum

The little wild chiles of the arid-Southwest (Capsicum annuum var. glabriusculum) have long held my interest. They are spread by the birds and crop up under shrubs or along fence-lines, where they seem to enjoy the shade. The tiny pods are scorchingly hot and the plants produce them prolifically without any apparent disease problems.

The first time I became aware of this plant I was in middle school. There was a crew working on the power lines behind my house and one of the workers was collecting the tiny red berries that we had assumed were poisonous. When my father asked him what they were, the worker apologized and asked if he could have them. Pretty soon, the worker realized we didn't know what they were. I don't remember how he explained, but it culminated with my dad trying one and then agreeing to let the worker have all that he had picked. Ever since then, the members of my family that like hot foods kept an eye out for the little wild peppers.

When I left Texas, I brought one of these chiles in a pot. Once in Minnesota, the plant quickly died. I had left it in a shaded location, like they prefer in Texas, but it was soon apparent that it also didn't like the cool and dark shadows found in Minnesota. I probably should have given it full sun, as full sun in Minnesota is much like partial shade in Texas.

Sometime before the plant died, I noticed that its leaves when crushed had a distinct smell I associated with the pungency of hot chiles. When I had my dad smell the crushed leaves, he jerked back in an attempt to avoid the pain you get when crushed chiles end up inside your face. He was very surprised at the scent and I was amused. I tasted some leaves to see if they had a hot taste, but they only tasted like greenery.

A few years later, I was visiting Austin-TX and looked for some of the wild chiles to gather seeds from. I succeeded in finding a single plant under shrub, but was surprised that the leaves had no scent at all. It was approaching mid-winter, so the lack of scent could have been due to the growing conditions or a difference in genetics.

I really liked the scented leaves, so if the seedlings I grow over the next year or so aren't scented I'll have to keep looking for plants that are on future trips to Texas.