See the blooming trees! April 09 2018, 0 Comments

Many people are surprised to learn that broadleaf trees are flowering plants. It is true that most of them do not have the showy blossoms that people associate with the word “flower.” Members of the rose and magnolia families aren’t subtle with their flowers. Any sighted person can tell they are blooming. 

Other kinds of trees may have quite inconspicuous flowers. The blooms may be so subtle that most people, including children, do not notice them. Help your children see these structures as they happen briefly in spring.

The red maples are among the first to bloom. Maples have a variety of flower structures and reproductive strategies. Some have yellow-green flower clusters that have both staminate and pistillate flowers. Others make extra staminate flowers and only a few with pistils.

Red maples are mostly dioecious – they have staminate and pistillate flowers on separate trees. I say “mostly” because I have seen and read other reports that a tree of one sex will sometimes have one branch that has the opposite sex flowers. This probably helps insure that pistillate flowers will receive the pollen they need to make seeds.

When the red maple starts to bloom, you may notice a red tint on the branch tips. If you can find a branch that is low enough for you to examine (try binoculars if the branches are too high), you will find one of two types of flowers. Neither has petals; both are small. The pistillate flowers (left) have two-branched stigmas showing. They are more intensely red than the staminate flowers (right), which look like a tiny pom-pom in reddish pink.

After the flowers bloom, the staminate flowers fall off. They have released their pollen, and their work is done. The pistillate flowers that received pollen continue to grow, and they develop long stalks with their young fruits at the end, often still bearing the drying stigmas. The fruits will become the maple keys; two grow joined together, but they split at maturity. This makes a maple fruit a schizocarp. Its two sections are samaras, winged fruits that the wind disperses.

Elms are another family of early bloomers. Their flowers are tiny, just two little furry stigmas surrounded by stamens. The developing fruits – again they are samaras – often color the tree a spring green and then turn brown before the leaves are completely unfurled.

Ask your children to think about the adaptation of blooming early, having wind-pollinated flowers, and having wind-dispersed fruits. They may be able to reason that the trees must bloom early so that their leaves won’t interfere with the pollen transfer. Some trees, like the elms, even disperse their seeds before the leaves block the wind from the mature fruits.

Swelling buds and developing leaves and shoots make great subjects for botany observation. Enjoy them with your children as the shoots and the spring develop.

Priscilla, April 9, 2018 

Plant surprises in the desert February 17 2017, 0 Comments

In January, I visited Tucson, Arizona and enjoyed exploring the Sonoran Desert. The plants there show many adaptations to the heat and dryness. The cacti and palo verde trees are what I expected. What surprised me is that plants I thought would need much more moisture are also able to survive in that climate.

There had been rain before my visit, enough that several hiking trails were impassable because normally dry creeks were flowing. As usual, if you want life, just add water. The plants that need moisture to reproduce, the spore-bearing plants, came out of hiding and were thriving. I saw a number of different ferns, but those weren’t a big surprise. I had seen ferns growing from cracks in lava flows before. The key for ferns seems to be finding a moisture-conserving crack on the shady side of a rock outcrop.

The spike mosses, genus Selaginella, were fluffed out and green. One of their common names is resurrection plant, so you can image how they look when they are dry. Spike mosses are not true mosses. They are members of the club moss lineage aka the lycophytes. One Sonoran species, Selaginella rupicola, is called rock-loving spike moss.  There were hillsides with many spike mosses protruding from cracks between rocks.

The mosses were looking very green and active. They are known for their ability to dry out and wait for water. They formed their green carpets out on more open ground and in sheltered rock overhangs. It was in one of the latter habitats that I found the big surprise. There were liverworts growing with the mosses.

Liverworts are the plants that have leaf pores that are always open. I think of liverworts as growing in habitats that have abundant moisture, not just isolated periods of wet weather. It is true that the liverworts in Oregon’s Willamette Valley survive the summer drought, but the humidity is never as low nor the temperatures as high as in the Sonoran Desert. The Sonoran liverworts are small, thalloid ones, much smaller than the ones native to western Oregon. They have the right appearance for a liverwort. They look like a flat leaf growing right on the ground, and they branch into two equal parts, which gives them a “Y” shape. They must have special adaptations and be very tough and resilient to live the desert.

Plants offer surprises in all habitats, not just the desert. You just have to take the time to look.