Vitis aestivalis (Summer Grape)

Plant Info
Also known as: Silverleaf Grape
Genus:Vitis
Family:Vitaceae (Grape)
Life cycle:perennial woody
Origin:native
Status:
  • State Threatened
Habitat:part shade, sun; average to dry; deciduous woods, thickets, wooded bluffs
Bloom season:June
Plant height:to 70 feet
Wetland Indicator Status:GP: FAC MW: FACU NCNE: FACU
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: indistinct Cluster type: panicle

[photo of male flowers] Cylindric clusters up to 6 inches long opposite the leaves of this year's new branches. Separate male and female flowers are typically on different plants, both 1/8 inch across or less with 5 green to yellowish petals that drop off early. Male flowers have 5 or 6 long, pale, erect to ascending stamens around a tiny button center. Female flowers have a bottle-shaped style and 5 short stamens that are usually sterile and somewhat contorted. The calyx cupping the flower is minute; flower stalks are minutely hairy and often red. Flowers are fragrant.

Leaves and stems: Leaf attachment: alternate Leaf type: lobed Leaf type: simple

[photo of leaves] Leaves are 4 to 8 inches long and about as wide, mostly broadly heart-shaped in outline, shallowly to deeply lobed with 3 or (usually) 5 major lobes and a broad gap between the 2 basal lobes. Deep sinuses between major lobes are often well-rounded. Edges are toothed, the teeth mostly rounded with a minute point at the tip.

photo of cobwebby leaf hairs] The lower surface is covered in a whitish, waxy bloom, which is often obscured by reddish-brown, cobwebby hairs; major veins are also densely hairy. The upper surface is dark green and hairless or becoming so. Leaf stalks are 2 to 6 inches long, often reddish, hairy, more densely so near the leaf blade and more sparsely near the stem.

[photo of shaggy bark] New branches are yellowish-green to reddish and hairy, the nodes covered in a waxy bloom. Forked tendrils develop opposite the leaves on first year branches, usually skipping every third leaf, and become woody with age. Older bark is brown to reddish-brown, hairless and shredding, peeling in long strips. A mature plant may have a trunk as much as 8 inches in diameter at breast height (dbh). Plants may climb high into trees or crawl over shrubs and lower vegetation.

Fruit: Fruit type: berry/drupe

[photo of developing fruit] The flower clusters become dangling as fruit develops. Fruit is a round berry ¼ to ½ inch in diameter, ripens from green to blue-black, and is covered in a white bloom. Inside a berry are 2 to 4 slightly flattened, egg-shaped seeds. Berries are often sour until after a frost, then turn more sweet-tart.

Notes:

Summer Grape a rare species in Minnesota, limited to a few southeast counties along the Wisconsin border, where it reaches the extreme northwest edge of its range. Across its range, it's found in upland hardwood forest and forest edges, dunes, fencerows, and wooded bluffs, often in sandy soil and in areas of disturbance (natural or man-made). According to the DNR, biological surveys in the southeast over the last 20 years have only found 1 new location, bringing the total to 11 known populations, one of which was unintentionally destroyed in an effort to manage specific canopy trees. This illustrates the problem of managing an entire ecosystem as component parts rather than as a whole. Its habitat preferences in MN are not well understood and it was listed as a Special Concern species in 1996, elevated to Threatened in 2013.

It can resemble the related Riverbank Grape (Vitis riparia), which has leaves with sharply serrated edges, lacks the cobwebby hairs and waxy bloom on lower leaf surfaces, and is ubiquitous in floodplain forests and woodlands throughout the state, where Summer Grape prefers drier habitats. Summer Grape leaves may also resemble another vine, Common Hops (Humulus lupulus), which does not have woody stems or tendrils, has opposite leaves, and a cone-shaped fruit rather than berries. There are 3 recognized varieties of Vitis aestivalis, distinguished by fruit size, degree of hairiness, the amount of waxy bloom and other traits; var. bicolor, a.k.a. var. argentifolia, is present in Minnesota. Note that the population we encountered had sparse glands on at least some new stem growth, but there is no mention of glands or glandular hairs in any of the available references.

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More photos

Photos courtesy Peter M. Dziuk taken in Houston County.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Annie H. - Hibbing
on: 2017-08-15 20:26:43

Along the wood in my back yard I have watched the Riverbank grape (https://www.minnesotawildflowers.info/shrub/riverbank-grape) grow. It is over 20 feet high along the treeline, and follows about 100 feet along the forest. This year, I noticed a smaller grape plant along the same line, with clearly different leaves. Deeper lobes, and shaped differently. It is now about 3 feet high, with 3 vines. It is this summer grape, I am sure. Now, according to the map, this summer grape is only in s.e. Minnesota - but we are up here in St. Louis County, 2 hrs west of Duluth.

Posted by: K. Chayka
on: 2017-08-16 05:54:50

Annie, what you saw was most likely moonseed. The leaves are variably lobed and can resemble southern grape.

Posted by: Annie H - Hibbing
on: 2017-09-02 03:05:23

I posted that I saw this plant, however, I now believe it is the riverbank grape, with deeper lobes. I have NO idea why the same genus would have 2 very different leaves, but it looks just like this one, but with the riverbanks spiky edges. It looks just like the top pic in summer grape vine, but with the tiny spikes along the leaves, like riverbank. Sorry I can't take pics. If you can delete BOTH of my posts, so I don't throw people off, I would appreciate it. :/

Posted by: K. Chayka
on: 2017-09-02 06:21:27

Annie, it's really not so unusual for a species to have variably shaped leaves. And keeping your comments online may actually help others who might have a similar experience.

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