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Catkins

Paper Birch Catkins: Winged Nutlets & Bracts Dispersing

12-8-15 white birch female catkin 005Paper birch (Betula papyrifera) produces separate male and female flowers on the same tree, both in the form of catkins (cylindrical clusters of flowers). The catkins form in the fall and overwinter in a dormant state. In the spring they mature as the leaves develop, becoming pendulous. Male catkins are 2-4 inches long, whereas female catkins are usually 1 – 2 inches long. Both lack petals, enhancing wind pollination. After fertilization occurs, the male catkins wither away, while the female catkins droop downward and become cone-like.

The female catkins consist of tiny winged nutlets that are located behind three-lobed, hardened, modified leaves called bracts (yesterday’s blog post) and are usually dispersed by the wind during the fall and early winter. Birch bracts are species-specific — different species of birch have different-shaped bracts, allowing one to identify the species of birch that a bract comes from.

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Beaked Hazelnut Flowering

beaked hazelnut 400The blossoms of many shrubs are not necessarily big, flashy, strong-scented flowers, especially if they are wind-pollinated and have no need to attract insects. Beaked Hazelnut’s flowers are now blooming – pendant male catkins loaded with pollen and ¼ “- diameter female flowers. The female blossoms should be examined through a hand lens – they are exquisite little maroon flowers with magenta highlights and pistils that curl this way and that, in hopes of catching pollen grains. One advantage to flowering now, before leaves are out, is that the wind-dispersed pollen has fewer obstructions.

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Pussy Willow Look-alikes

4-14-15  trembling aspen male catkins IMG_4438The flower buds of Trembling Aspen (Populus tremuloides) look a lot like pussy willows when they first open up and the tip of the catkins (flower spikes) emerge. Long before the leaf buds open, the flower buds swell and their scales open to reveal male and female flowers that mature into pendulous catkins (male and female catkins are on separate trees). In a month or so, after pollination, the seeds that have developed on the female catkins will be dispersed by the wind and the air will be filled with cottony fluff. (photo: male Trembling Aspen catkins)

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Pussy Willows Emerging

2-12-15 026Even with sub-zero temperatures and feet of snow on the ground it is possible to find signs, such as pussy willows, that spring really is around the corner. What we call pussy willows are, in fact, the soft, silvery hairs that insulate the emerging spike of flowers, or catkin, within a willow flower bud. A willow catkin consists of all male or all female flowers. The first catkins to emerge in the spring are usually males. The hairs, or “pussies,” that emerge when willow buds first open trap the heat from the sun and help warm the center of the catkins, where the flowers’ reproductive parts are located. This trapped heat promotes the development of the pollen (or in female flowers, the ovules) of the flowers deep within the hairs. Eventually the reproductive parts of the willow flowers – the stamens and pistils – emerge, but until they do, we get to enjoy their silvery fur coats.

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Speckled Alder in Winter

2-3-15 speckled alder 166Speckled Alder is a shrub in the Birch family that is found growing in wetlands. It is named after the “speckles” on its bark — horizontal lines or lenticels (spongy openings for the transfer of gases). In winter, Speckled Alder branches are distinctive because they carry two kinds of buds as well as last year’s fruit. The male flower buds are in the form of inch-long catkins which appear reddish in winter. They begin to turn yellow in March just before they extend into long, yellow pollen-bearing flowers. The female flower buds are small and drooping just ahead of the catkins on the branch. They look like miniature unopened versions of the seed-bearing fruit they’ll become. Last year’s woody fruit, or “cones” are also present, having opened and had their seeds, or winged nutlets, dispersed by the wind last fall.

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Aspen “Snow”

5-27-13 poplar fruit 004Even though it snowed in Vermont this weekend, there is something else white and fluffy that is also being blown about, and it doesn’t melt when it hits the ground. The tiny white bits of fluff that are floating in the air are the seeds of aspens (also referred to as poplars), primarily Bigtooth Aspen (Populus grandidentata), that are borne in capsules that develop along a 3 to 6-inch dangling stem. These former flower clusters, and the capsules and seeds they developed into, are referred to as catkins. The capsules split apart when the seeds are mature, releasing the cottony-tufted seeds that are well-designed for dispersal by the wind. Looking into the fluff-filled sky, it’s not hard to believe that a single Bigtooth Aspen tree can produce over a million seeds.