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Common Milkweed - Phenophase Definitions

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Common Milkweed (Asclepias syriaca L.)

milkweed pre-flower growth

Pre-­‐flower growth early June. P. Bell, SOS observer

Directions: As you report on phenophase status (Y, N or ?) on the datasheets, refer to the definitions on this sheet to find out what you should look for, for each phenophase in each species. To report the intensity of the phenophase, choose the best answer to the question below the phenophase, if one is included.

Leaves

Initial growth: New growth of the plant is visible, either from above-ground buds with green tips, or new green or white shoots breaking through the soil surface. Growth is considered “initial” on each bud or shoot until the first leaf has fully unfolded.

early flower growth of milkweed

Early flower growth. P. Bell, SOS observer

Leaves: One or more live fully unfolded leaves are visible on the plant. For seedlings, consider only true leaves and do not count the one or two small, round leaves (cotyledons) that are found on the stem almost immediately after the seedling emerges. Do not include dried or dead leaves.

Flowers

Flowers: One or more fresh flowers or flower heads (inflorescences) are visible on the plant. Flower heads include many small flowers that usually do not open all at once. Do not include wilted or dried flowers that remain on the plant, or heads whose flowers have all wilted or dried.

Common milkweed inflorescence with some open flowers

Common milkweed inflorescence with some open flowers. P. Bell, SOS observer

How many fresh flowers or flower heads are present?

Less than 3; 3 to 10; More than 10.

Open flowers: One or more open fresh flowers are visible on the plant. Flowers are considered “open” when the reproductive parts (male stamens or female pistils) are visible between unfolded or open flower parts. Do not include wilted or dried flowers that remain on the plant.

How many fresh flowers are open?

Less than 3; 3 to 10; More than 10.

Common milkweed pods

Common milkweed pods. J. Appollonio, UMaine

Fruits

Fruits: One or more fresh fruits are visible on the plant.

How many fresh fruits are present?

Less than 3; 3 to 10; More than 10.

Ripe fruits: One or more ripe fruits are visible on the plant.

How many fruits are ripe?

Less than 3; 3 to 10; More than 10.

Recent fruit drop: One or more fresh mature fruits or seeds have dropped or been removed from the plant since your last visit. Do not include obviously immature fruits that have dropped before ripening, such as in a heavy rain or wind.

Common milkweed seed pod releasing seeds

Common milkweed seed pod releasing seeds. Rob Routledge, Sault College, Bugwood.org

How many mature fruits have dropped?

Less than 3; 3 to 10; More than 10.


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