Silver Maple
Marion Cemetery, Marion, Ohio
March 17, 2009

The first tree flower of spring, silver maple (Acer saccharinum, family Aceraceae) is an abundant species of moist or wet soil. It is commonly planted along roads, and in parks and cemeteries such as the Marion Cemetery in Marion, Ohio. Silver maple flowers are inconspicuous, but often get noticed as an early sign of spring, albeit slightly misinterpreted as people cheerfully report seeing maple "buds."  Actually, silver maple buds are evident throughout the winter, and the striking change we see in early-mid March is the actual emergence of flowers from the buds  

Over the winter, silver maple flowers were contained within globose clusters of lateral buds. Here's what their twigs looked like during midwinter, 2008.


Like many tree flowers, silver maple sexual expression isn't very clear-cut. At the Marion Cemetery, some individual trees seem to have only flowers all of one sex, either male ot female but not both. Yet some had both male and female flowers, located on different parts of the tree. And some seemingly pistillate (female) flowers appeared to have stamens, but they were tucked deep in the blossom, unexpanded.

For interpretive guidance, it helps to consult a detailed and authoratative botanical manual. Here's what H.A. Gleason said about maples in the best book ever written, New Britton and Brown Illustrated Flora of the Northeastern United States and Adjacent Canada:

That helps. We're looking for unisexual flowers, but they might only be "functionally" unisexual, i.e. possessing vestigial organs of the unexpressed sex. Further, Gleason tells us that silver maple flowers lack petals, and, moreover, that each flower cluster is either wholly staminate or wholly pistillate. Although the manual doesn't say so, it seems like some trees are wholly staminate, some are wholly pistillate, and still others are a mixture (monoecious). The following pictures are from separate trees, both of which appear to be unisexual.

Here are male flowers. Note the slender filaments sticking pollen-containing anthers well out into the breeze. (The species is wind-pollinated.)

...And here are the female ones. Note the two elongate style-branches, well positioned to receive wind-borne pollen.

While scouting the vicinity west of Marion near the Little Sandusky River for suitably photogenic silver maples, it was a thrill to see a bald eagle flying overhead, attracting also the attention of a red-tailed hawk.

Skunk cabbage.
Delaware County, Ohio.
March 8-13, 2009.

The first wildflower of spring, skunk cabbage (Symplocarpus foetidus, family Araceae) is a rugged and long-lived perennial that can be extremely abundant in open bottomlands such as this area along a tributary to Alum Creek in eastern Delaware County, Ohio.

Skunk cabbage is famous for its ability to generate heat and plants can sometimes be seen iconically poking their noses through a late-winter blanket of snow, as seen last year at this same location.

The arum family is distinguished by a unique type of inflorescence consisting of a dense flower spike, the spadix, situated beneath a large overarching bract, the spathe. A familiar example is the woodland wildflower Jack-in-the-pulpit (Arisaemia triphyllum) wherein the spadix is the preacher "Jack" and the spathe is his pulpit. Another arum species, green dragon (A. dracontium), looks like a dragon, I guess. Here's what these two woodland wildflowers looked when they were blooming in mid-May within the past few years.


The skunk cabbages are in full bloom this week. Here's a typical pair of inflorescences, wherein only the spathes are visible, as each spadix is nearly completely concealed within its spathe. To more fully understand these inriguing (and very abundant) flowers, I sectioned a spathe to expose the spadix within.


Surprise! These plants are not dioecious or even monoecious; the flowers are "perfect" (hermaphroditic, bearing both stamens and pistils). It is evident therefore that skunk cabbage exhibits "protogyny," a sequential maturation of the differently sexed flower parts, wherein the female pistil ripens first.

The following is a studio portrait of a portion of a spadix during the early, female, stage of flowering. Using a sharp razor blade, a thin tangential slice was made through through the spadix, resulting in an upper  cross-section of several flowers, exposing and making evident some of the floral features spelled out in the Gleason synopsis. Progressing inwards these are:  the 4 perianth segments, the anther portions of the 4 stamens, and the central angular style portion of the pistil. In the unsectioned face view, the upper portions of the perianth segments and the stigma portion of the pistil are visible, but the stamens are not.