Nov 082019
 

Evergreen forest floor plants are an under-appreciated feature of late fall

At first glance, a walk in the November woods seems uneventful, with little of interest to catch our attention. Yet, this is a wonderful time of year to focus on elements of the forest that we may have missed in the green blur of summer. Of particular interest is the beauty and diversity of our evergreen mosses, club-mosses, ferns, and even wildflowers. Standing out like green beacons against the faded browns and yellows, it’s as if they are calling out: “Come and take a look at me!”

Evergreen plants are excellent examples of adaptations to the shorter growing season of northern ecosystems. Since they don’t shed their leaves, these plants can begin photosynthesis as soon as the snow cover melts. They can also continue to produce food later into the fall. Because water is unavailable in the winter – locked up in the form of ice – some of these plants have waxy coatings on the leaves to limit water loss. This is particularly noticeable in evergreen wildflowers like wintergreen and pipsissewa.

Mosses

One of the first things we notice when we start paying attention to the denizens of the November forest is the abundance of mosses. Emerging into clearer view now that the profusion of summer foliage has retreated, mosses are usually found on boulders, tree stumps, rotting logs, and around the base of trees. They come in dozens of shades of green, ranging from shiny emerald to almost black. Take time to get down on your hands and knees to examine them carefully. It is like entering a verdant Lilliputian forest.

Mosses are flowerless plants that evolved millions of years ago from algae. Given their aquatic origin, they are believed to be among the first plants to emerge from the water and to adapt to terrestrial life. Some species still grow submerged in streams. Mosses have tiny stems and leaves, but the stems only serve as a support for the leaves and do not actually conduct water or food to other parts of the plant. Even the rhizoid filaments that anchor the moss to the ground, rock or tree bark are not true roots, since they play no part in absorbing water or minerals.

Like nearly all woodland evergreen plants, mosses grow in small colonies that spread through vegetative reproduction by putting down new rhizoids. However, new plants can also grow from spores. Spore‑based reproduction is complicated but very interesting.

Moss really consists of two distinct generations – the green, leafy gametophyte and the wiry and leafless sporophyte with the capsule on top. When they are ripe, the capsules open and the spores are dispersed. If a spore lands on a surface with enough moisture, it will begin to grow into a mass of green hairs. Buds appear on these hairs, which grow into stems with narrow leaves. These structures are called gametophytes. Some of the stems will produce either male or female sex organs among clusters of leaves at the top. Sperm produced in the male organ use a film of water from rain or dew to swim to the female organ on another stem. In this way they fertilize the egg. The embryo, embedded in the cluster of leaves surrounding the female organ, then grows to form a sporophyte, which is the familiar wiry stalk with the capsule at the end. The base of the sporophyte remains anchored in the cluster of leaves at the top of the female gametophyte. The latter essentially becomes host to the parasitic sporophyte. Spores develop in the capsule which disperse, germinate and repeat the cycle.

The Kawarthas is home to dozens of species of mosses. In conifer swamps, different types of sphagnum (peat moss) usually dominate. They are spongy and can form carpet‑like mats. Other common groups of mosses include the upright species such as juniper and hair‑cap moss, hummock forming species like pin cushion moss, and creeping mosses like shaggy moss.

Club-mosses

Club‑mosses, too, are a key feature of the late fall woods. The strange name stems from their moss-like appearance – at least at first glance – and from the club-like structures that project from the plants.  Some species look like tiny, ten-inch-tall coniferous trees. Club‑mosses usually grow in the rich, shaded soils of mixed deciduous and coniferous woods. They often form colonies that can cover large areas of the forest floor. Individual plants are connected by horizontal stems that run above ground (runners) or below ground (rhizomes). These plants are a close relative of ferns and reproduce both vegetatively and by spores. They were among the first plants to develop true roots, stems and leaves, along with cells capable of transporting water long distances. Three hundred million years ago, club-mosses grew over 30 metres tall and dominated the great coal swamps of the Carboniferous period. You can thank (or curse) them for the gasoline you burn in your car.

There are several club‑moss species or “lycopodiums” that you can expect to find during a woodland walk in Peterborough County. Ground‑pine (Lycopodium dendroideum) has a symmetrical shape that resembles a tiny pine tree. This probably explains why ground-pines are sometimes used as Christmas decorations. The spore‑bearing leaves are tightly clustered at the tip of the stem and form a yellowish, cone‑like structure called a strobilus. It is composed of sporangia, which produce numerous minute spores. The spores germinate to form the small, leafy stage of the plant’s life cycle known as the gametophyte. The life cycle then continues in a manner similar to mosses.

Club-moss spores are packed with fats and oils, which make them both inflammable and water‑repellent. Northern Europeans collected the spores in the 19th century to use in the manufacture of fireworks, as a substitute for talc, and as a source of illumination in early photography.

Shiny club‑moss (Lycopodium lucidulum) has glossy, needle‑like leaves and grows from a horizontal stem that is usually hidden in the leaf litter. Bright yellow spore cases appear on the upper surface of the last leaves produced each growing season. You should also watch for ground‑cedar (Lycopodium complanatum), interrupted club‑moss (Spinulum annotinum), and wolf’s claw club‑moss (Lycopodium clavatum). All five species often grow in close proximity.

Ferns and wildflowers

Several species of ferns are also evergreen. Probably the most common is the marginal woodfern (Dryopteris marginalis). These attractive, dark green ferns have widely arching crowns and are common in mixed forests, especially on the Canadian Shield. They keep their fronds (leaf-like structures) for one year before replacing them in the spring. In late fall, the stalk softens, and the formerly erect fronds lay flat on the ground. They then survive the winter – still green – under the snow. By laying flat, the fronds suffer less frost and mechanical damage. They are capable of photosynthesis as soon as the snow melts and the fronds are exposed to the spring sun. In this way they take advantage of the intense light available on the forest floor prior to leaf-out.

The Christmas fern (Polystichum acrostichoides) is another attractive species to watch for. Its name comes from the leathery, spiny‑toothed leaflets, which are reminiscent of holly and from the fact that the plant is still green at Christmas. It is sometimes used as a holiday decoration. I have had both Christmas ferns and intermediate woodferns in my gardens for years. Keep an eye open, too, for rock polypody (Polypodium virginianum), a small fern that grows mostly on rocks and boulders in cool, shaded areas.

Coniferous and mixed forests are also home to a variety of evergreen wildflowers. Many look as luxuriant in winter as in summer. Pipsissewa, for example, has glossy, dark green leaves. Watch also for trailing arbutus, goldthread, partridgeberry, twinflower, and winterberry. The berries and leaves of the latter have a pronounced wintergreen taste and are pleasant to chew. The Nanabush Trail at Petroglyphs Provincial Park and Bonny’s Pond trail at Silent Lake Provincial Park are excellent locations for most of the evergreen plants mentioned in this article.

 What to watch for this week

Snowshoe hares and weasels are now acquiring their white winter coats. In the case of the hare, the ears and feet turn white first, while the back is the last part of the body to change colour. Except for the black ear tips, snowshoe hares are usually completely white by early December. Both the short-tailed (ermine) and long-tailed weasel also turn white, except for the last third of the tail, which remains black year-round.

Climate Crisis News

The world’s largest oil and gas companies would need to slash their production by more than a third by 2040 to meet international climate targets, according to a new report from Carbon Tracker. You can read the report at carbontracker.org/reports/balancing-the-budget/. The seven listed oil majors, which include ExxonMobil, BP, and Shell, would need to cut daily production by 35 percent to avoid driving temperatures 1.5 degrees C higher than pre-industrial levels. This means that governments would also need to stop issuing new oil and gas licenses for fossil fuel exploration. The report showed that global oil projects that have already been approved are almost enough to meet demand in a 1.6 degrees C scenario and there is “very little headroom for new fossil fuel projects.” Reports such as these question the advisability of  any future expansion of the Alberta oilsands.

 

 

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