Acer rubrum

Family / Families: Sapindaceae
Scientific Name(s): Acer rubrum L.
Location(s): North Carolina, USA (assumed)
Entry Author(s): Dominic Janus
Copyright Holder(s): Brandon Gerringer@Flickr
Image Permissions: Please contact the copyright holder for permission to use.
Photographer(s) Appreciation: We're thankful to Brandon Gerringer@Flickr for sharing one of his photographs of Acer rubrum coming into flower.
Tags: named by Linnaeus, Sapindaceae, Sapindales, via Flickr

The male flowers of Acer rubrum

Although Acer rubrum grows in UBC Botanical Garden as part of its significant collection of maples, here’s a photo of a plant coming into flower from across the continent in its native range. Acer rubrum, or red maple, is among the most abundant native trees of the eastern United States.

Typically ranging from 9 to 28 m tall (30-90 ft.), red maple is distributed from the southern parts of eastern Canada south to states bordering the Gulf of Mexico. Perhaps once confined to as little as 5% of the forests in this large area, the density of red maple has increased up to 7-fold over the years (Wikipedia, citing the US Forest Service). As a result, red maple now seems to outcompete other trees in forests previously dominated by oaks and hickories. An article written in The New York Times explains this “reddening” of forests. The increased abundance is partly due to the practice of fire suppression, which allows it to thrive in areas where its growth was once limited due to its intolerance of fires.

Also in its favour is its high tolerance to a range of soil moisture conditions and pH. Red maples can quickly establish at sites ranging from dry areas to swamps (other common names include swamp maple and water maple). Its ability to alter its root growth in response to soil conditions is the source of this adaptability. In wet locations, a short taproot with longer lateral roots is grown to avoid the saturated soil layers. In dry conditions, however, plants prioritize growth of the taproot to exploit the deeper and wetter soil. A term for this common phenomenon present to different degrees through all taxa (though particularly so for plants) is phenotypic plasticity (an organism’s ability to alter its growth form in response to different environments). From a plant evolution perspective, the ability of an individual plant to adapt to a changing environment is critical to its success (as plants typically cannot move…).

Pictured here are the male flowers of red maple. Photographs of both the male and female flowers of Acer rubrum are present in the BPotD Flickr Pool. Today’s flowers were photographed on February 14 of this year; in its range, Acer rubrum is one of the first plants to flower in spring. The leaves exhibit some variation in morphology, but they typically have three serrated, triangular lobes. Alluded to in the name and specific epithet, rubrum (red), essentially every visible part of a red maple is coloured red to a certain degree (excluding the bark). The flowers and fruit (samara) remain red throughout their development, while the twigs, young stems, buds, and especially leaves exhibit are a stunning red in the autumn.

Red maple’s Wikipedia page also notes its allergenic potential, a trait that varies between cultivars. Many of these cultivars are grown in urban environments, and were selections made for high tolerance to urban environmental factors. One tidbit of information about the leaves is that they are extremely toxic to horses–if ingested by horses, a dose of approximately 1400 grams (3 lbs.) is almost certainly lethal.

Red maple is the state tree of Rhode Island. It is one of the three main species used in maple syrup production; of these, it has the shortest season and lowest sugar concentration in its sap (PDF)–still, it produces enough to make the venture worthwhile.