// Twitter Cards // Prexisting Head The Biologist Is In: July 2015

Tuesday, July 28, 2015

Botanizing in Alaska: Twin-Flower

This plant was found growing on my fiancé's father's property. It goes by the name Twin-Flower (Linnaea borealis) due to the tiny paired flowers it produces. The flowers are short-lived, making it lucky that I was able to find and photograph this specimen. By the end of my week in Alaska, every flower in the patch had fallen.

The plant grows as a woody vine, growing up to a couple meters long. It doesn't climb like most vines, however. The plant spreads out into a wide mat, with each branch growing new roots periodically. It likes to grow under conifers, and is often found overgrown with mosses.


Thursday, July 23, 2015

Botanizing in Alaska: Dwarf Birch

I found this tree trunk on a rocky outcrop at the top of a mountain just outside Fairbanks, Alaska. The wood was spread over a foot or so, though I didn't have a measuring-tape handy to get a precise measure. The cold and exposed environment suggests that the tree would have grown very slowly and may be anywhere from decades to hundreds of years old.

In this environment, strong winter winds quickly abrade away overly-exposed living material. Dead material doesn't last very long either. Yet this tree remains alive, with vital growth attached to the dead wood at the lower-right and upper-left.

It was only by comparing the above tree to something more youthful (at right) that I was able to identify it as the Dwarf Birch (Betula nana). Forests of this tree can be ancient, but only inches tall.


Thursday, July 9, 2015

Botanizing in Alaska: Mountain Avens

The Mountain Avens (Dryas octopetala) is a circum-arctic subshrub, growing up to a meter across while reaching only a few centimeters tall. The flowers typically have eight petals (hence the name octopetala) and track the arctic sun as it rolls around the summer sky. This heliotropism is thought to help the flower warm up so it can mature its seeds more quickly. There are several subspecies, including the Alaskan form (D. octopetala ssp. alaskensis), but little information is available about the differences between the forms.

Since I found them after the flowers were long gone, identification was a bit trickier. The seed-heads reminded me of those from the Pasqueflower (Pulsatilla), so I started my searches there. The leaves are distinctly different, however, so I meandered into looking at images of arctic wildflowers from Alaska until I found an image that had the right leaves. I was lucky in that the site included an ID of the plant, which I rapidly confirmed elsewhere.

Supposedly the plant takes well to garden culture, though its short-stature would make it sensitive to being overgrown by aggressive weeds when in a warmer climate. I did collect a few seeds, so I hope to see how it does here.


Saturday, July 4, 2015

Botanizing in Alaska: Wild Iris

I just returned from a week-long trip to Fairbanks in central Alaska. I quickly noted the abundant wild irises (Iris setosa interior) in bloom around the city. The species is endemic through much of Alaska, with a few regional subspecies/varieties. It goes by a few different common names. "Beachhead Iris" seems to be the most common, though I prefer "Alaska Iris" for the plants I encountered because it more clearly refers to the specific Alaskan sub-species.

While I was there, the local paper (Fairbanks Daily News-Miner) published an article about Jack Finch, a metalworking instructor at the local university, who has a long-running hobby of breeding I. setosa.


Though we tend to refer to all the colorful floral structures of a typical garden iris as "petals", the structures are botanically divided into the true petals (upright standards) and petaloid sepals (descending falls). In I. setosa, the botanical petals are reduced so severely that the flower appears to have only three "petals". Jack Finch occasionally sells plants in Fairbanks, which probably helps explain the diversity of colored forms I found in gardens during my week.

NewsMiner photo.
In addition to numerous shades, Jack Finch also isolated a recessive mutation which converts the tiny petals of the wild flower into full-sized sepals (thus producing an attractive and larger flower). I never did find an example of this flower, but the newspaper published a photo which nicely illustrates the variation.

During my trip I was able to collect seeds from several plants with different colored flowers. As the plants were in full bloom, the only seeds to be found were those left-over from the previous season or two. Hopefully they remain viable so that when I plant them this fall (for cold-stratification) they can start growing in spring.

The Iris genus is subdivided into several sub-genera, which are then in turn subdivided into several series of species. For the wild Iris setosa I was so admiring, the full nomenclature is something like: [Genus = Iris] [Subgenus = Limniris] [Series = Tripetalae] [Species = setosa] [Subspecies = interior].

Species definitions in plants are often less strict than they seem to be for animals. Some research from a few years ago sought to identify how I. setosa was related to other North American wild irises. They found I. setosa was most likely one of the parents (with I. virginica) of I. versicolor. I. setosa and I. virginica are both diploid with 38 (19/19) and 70 (35/35) chromosomes, respectively. The hybrid between the two species is infertile due to mis-paired chromosome sets (19/35). But like in other cases (http://the-biologist-is-in.blogspot.com/2015/01/hybrid-sterility-and-speciation.html), that infertility can be resolved by a whole genome duplication like that which appears to have happened in the ancestors of modern I. versicolor.