Autumn Olive - Elaeagnus umbellata

Here is a month-by-month outline of the life cycle stages of woody invasives in Southeast Michigan, framed entirely in ecological/phenological terms. focusing only on growth, reproduction, and dormancy patterns that matter for understanding how this species behaves through the year.

January – February

• Plants remain fully dormant.

• Leaves are absent; branches retain their twigs

• Mature shrubs often hold onto persistent berries from the previous fall.

• Roots remain alive and ready to resume growth when soil temperatures rise.

March

• One of the earliest woody species to break dormancy.

• Sap begins to flow before many natives.

• Swelling of buds occurs as day length and temperatures increase.

April

• Leaf-out begins, typically earlier than most native shrubs and trees.

• The plant gains a head start on photosynthesis while native species are still bare.

• Root growth also resumes actively in warming soils.

May

• Vigorous shoot elongation continues.

• Often flowers before many native shrubs flower.

• Flowering occurs while leaves are fully expanded, taking advantage of high light conditions before canopy closure.

June

• Fertilized flowers develop into small green berries.

• Leaf canopy is fully developed, dense, and shade-producing.

July – August

• Berries enlarge and turn green to appropriate color

• Shrubs maintain dense foliage, often shading out herbaceous understory growth.

• Stems continue secondary thickening; root reserves build steadily.

September

• Fruits ripen and persist into fall.

• Leaf canopy remains dense while many natives begin senescing.

• Seeds are viable and ready for dispersal. Birds and mammals begin consuming fruits, dispersing seeds across the landscape.

October

• Leaves remain green much later than most native trees and shrubs.

• Fruits continue to be available and dispersed.

• Delayed senescence provides continued photosynthetic advantage compared to natives.

November

• Leaves may still be present after most native species have dropped theirs.

• Eventually, hard frosts trigger leaf drop, though often weeks later than native woody plants.

• Roots store carbohydrates over winter, supporting next year’s early growth.

December

• Plants are bare of leaves.

• Berries may persist into early winter, continuing to be dispersed by birds.

• Stems and roots remain dormant, maintaining stored reserves.

Key Ecological Notes

• Extended growing season: Leaf-out occurs early (March/April) and senescence occurs late (October/November), giving the plant several extra weeks of photosynthesis compared to native shrubs.

• Seed dispersal: Fruits ripen in fall (September onward) and remain available through winter, ensuring continuous dispersal.

• Growth strategy: Dense foliage, rapid spring development, and late persistence create strong competitive suppression of native species.

Leaves are dark green / gray above and silver below and have a wavy edge

Stems are silver to golden brown and frequently have thorns

HABITAT—AOV prefers full sunlight and moderate to well-drained soils, but can grow in a wide range of conditions. It is tolerant of drought, nutrient-poor soils, and soil contaminants, but intolerant of wet soils. In the OOR AOV has been found on sand dunes, in and at the top of floodplains, near vernal pools and ponds, and along roads, ditches, and streams.

IDENTIFICATION—Habit: Deciduous, woody shrub to shrubby tree, reaching heights and widths up to 30’. Polygamodioecious. Rounded crown with dense branches.

Leaves: Alternate and oval to lanceolate, with blunt to pointed tips. 1-4” long and 1/2-1 1/2” wide. Smooth, but slightly wavy margins. Dark green to gray-green above, silver-white below.

Stems: Single or multi-stemmed. Twigs are silvery or golden brown and scaly when young. Older bark is smooth and brown-grey, occasionally fissured. May have thorns several inches long on spur branches.

Flowers: Small, fragrant and white to light yellow. Borne in clusters of 1-10 along twigs. Tubular, with 4 petals. 1/3-1/4” in diameter.

Fruits: Fleshy and silvery-green to brown, ripening to pink to red. Round to ovoid, <1/2” in diameter. Dotted with silver or brown scales, giving them a sandpapery texture. Edible, and rich in lycopene. A single mature AOV can produce up to 30 lbs. of fruit per year.

Seeds: Yellow-brown and 3-9 mm long. Dispersed by gravity, birds and mammals. One seed per fruit.

Roots: Have nitrogen-fixing nodules, allowing them to colonize inhospitable soils.