American Elm

A seven point five meter vase shaped elm tree covered in green flower buds in bright sunlight beside the western wall of Grove Street Cemetery and in front of Benjamin Franklin College.

Basic Information

Tree ID:

142

Family:

Ulmaceae

Genus and species:

Ulmus americana

Description:

Found exteriorly bordering the western wall of the Grove Street Cemetery on Lock Street across from Yale Health, this tree may be identified by its snapped, still attached branch. Its canopy spans over the cemetery wall and shades the sidewalk for passerby. This is a relatively young elm with a narrow trunk and height of only twenty four feet.

Surveyors:

Odera Nweke and Jack Parker

Location

Area:

Prospect and Sachem

Collected Data

Tree shape:

Vase-like shape

Date of tree entry:

02/16/2022

Height:

7.50 m

Diameter at breast height:

0.22 m

Bark

The bark of the tree is a granite gray colored periderm (dead tissue) with a few veins of exposed tawny colored cambium (living phloem). The pattern of the bark is of long, lenticular (tapering at either end) strips of periderm. On this tree, there is a slight green hue coming from the lichen growing on the bark. The ridges in the bark on this tree are shallow, but much deeper on larger elms. In larger elms, the bark pattern is sometimes densely-packed parallel strips of periderm, and sometimes large, interweaving strips that create a "lace" pattern of rhombuses.

Twigs & branches

The branches have a sinuous axis and maintain a constant diameter along their lengths. The branching pattern is a series of y-shaped forks with an angle of about thirty degrees and equally sized daughter branches. At approximately three meters up, the trunk splits in this pattern into two main trunks. Most elm trees typically have two or more main trunks comprising the top half of the three (Tree Musketeers), which gives this specimen its vase-like shape that the Morton Arboretum describes as "fountain-like." According to the USDA, some cultivars have been produced that are identifiable by characteristic differences in their branch structure, such as the "columnaris," "ascendens," and "pendularis." This specimen has a notable broken branch that still hangs semi-attached too strongly to be removed. For that reason, I nicknamed the tree "Twiggy."

Foilage

The American Elm is a deciduous dicot angiosperm with alternating, simple leaves. The leaves are elliptical with a doubly-serrate margin, a rounded base, and an acuminate apex. The elm is prototypical of "pinnate venation," in which the veins originate from along the length of a central vein called the midrib that extends from the petiole to the apex. The venation may be described as a "chevron" or "fishbone" pattern. Note that the vein origins along the midrib alternate from one side to the other.

Reproductive Structures

The appearance of the flower buds in spring depends on latitude: according to the USDA, they appear in early February in the South and in May in Canada. For this specimen in New Haven, Connecticut, the flower buds appeared in late April. Leaf flush is expected 2-3 weeks after the flower buds appear. For the northern climates, seed fall is expected in mid-June. The flowers droop down in bundles of 3 or 4. The outer sepals are whorled into a thin calyx with a violet tinge. The large, bright red anthers on white filaments are the most noticeable, but the style may be identified up close by its white, feathery appearance.

Fruit

The fruit of the elm is a winged covering over the seed called a samara. According to Minnesota Wildflowers, the elm samara is noted for being "flat, egg-shaped, surfaces hairless but with a dense fringe of short, white hairs around the edge, the tip often cleft with two hook-like lobes." This fruit shape will glide on the wind to spread the seeds when they fall. The samaras of this specimen appeared in late April 2022. Both the samara and the fallen seed are edible. According to Thayer (2006), the samara is best eaten as soon as it appears while still fully green on the tree.

Seasons

The Elm as it appeared when it was first identified on February 16, 2022
The samaras first appearing in late April
A shed leaf from the tree in February

Research

Natural range of distribution:

Habitat:

The American Elm occupies the eastern half of North America across a wide latitudinal range from the Gulf of Mexico along the entire eastern coast up to Nova Scotia. The western limits range from southern Saskatchewan to central Texas. This range varies in humidity, rainfall, and temperature. The American Elm is a major canopy component of the temperate deciduous forests of North America.

Origin, history, and uses:

According to the USDA, the interlocked grain of elm wood makes it very hard and resistant to splitting, which makes it ideal for items like hockey sticks or wherever bending is needed. It is one of the woods recommended to use in making bows for archery. The wood is mostly used for its hardness in furniture or construction, or occasionally as a veneer.

The American Elm was once much more common in North America (giving so many towns their “Elm Street”) but from the 1930’s onward, a fungal plague known as the “Dutch Elm Disease” carried by the bark beetle decimated the population.

New Haven, Connecticut (the home of this tree) gained its moniker “the Elm City” from its public tree planting program. The USDA says, “The American elm was prized for its use as a street tree. It was fast growing, hardy, tolerant to stress, and appreciated for its characteristic vaselike crown. Beautiful shaded streets in many cities attested to its popularity.”

The samaras and seeds are edible by humans and are also fed upon by “mice, squirrels, opossum, ruffed grouse, Northern bobwhite, and Hungarian partridge” (USDA).

Phenology:

The American elm tree begins producing fruits at around 15 years old, but in small amounts. When the tree has aged to about 40 years old, the fruits are produced in larger amounts and these start to appear during the spring when pollination has begun. Trees as old as 300 years have been observed to still produce viable seeds. Elm trees lose their leaves in winter and recover them two to three weeks after flowers appear. The appearance of flowers varies based on latitude, from February in the American South to May in Canada. Pollination occurs by wind and seed production begins shortly after. Frosting in the spring in the spring is deleterious to seed production. Most seeds will germinate within two weeks after falling.

References:

https://www.minnesotawildflowers.info/tree/american-elm

https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/ulmus/americana.htm

https://en.wikipedia.org/wiki/New_Haven,_Connecticut#:~:text=New%20Haven…

https://mortonarb.org/plant-and-protect/trees-and-plants/american-elm/

Media and Arts