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Alnus incana subsp. rugosa

Speckled Alder · Tag Alder

Family BetulaceaeGenus Alnus

Also published as Alnus rugosa. You are in the right place.

Two long hanging male catkins, yellow-green speckled with brown, on a thin twig against a black background
FlowerKenneth Dritz, USDA NRCSPublic domain

About the plant

What it is and where it grows — not part of any germination protocol.

Habit
shrub or treePlants of the World Online

Toxicity is noted only where a source states it. No note here is not a finding of safety.

Source: Plants of the World Online — Royal Botanic Gardens, Kew.

This source reports three treatments. All are shown.

Protocol 1

DerivedN. C. Deno, 1996

Difficulty Very high Rated by us, not by the source.

  1. Sow outdoors and leave it

    Up in May and June.

No stated waiting before sowing.

3% germination.

This source doesn't state how long step 1 lasts.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Alnus p. 18Public domain
Show the original text
Alnus (Betulaceae). All samples were received in March, and had already undergone at least 6 m of DS and probably more. Since DS was clearly detrimental in A. rugosa germ. 70L(1%), 40-70D(2%), and 3% in May and June in OT. None germ. in 70D or 70 GA-3.
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Alnus p. 18. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list.

Protocol 2

DerivedN. C. Deno, 1996

Difficulty Very high Rated by us, not by the source.

Start around December 15, 2026 for a May 3 last frost.

  1. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  2. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C Light: dark

about 3 months from start to step 2. Germination happens during step 2; time not stated, 21 days assumed.

2% germination.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Alnus p. 18Public domain
Show the original text
Alnus (Betulaceae). All samples were received in March, and had already undergone at least 6 m of DS and probably more. Since DS was clearly detrimental in A. rugosa germ. 70L(1%), 40-70D(2%), and 3% in May and June in OT. None germ. in 70D or 70 GA-3.
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Alnus p. 18. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list.

Protocol 3

DerivedN. C. Deno, 1996

Difficulty Very high Rated by us, not by the source.

Start around March 15, 2027 for a May 3 last frost.

  1. Sow and cover

    Temperature: 70°F 21°C Light: light

No stated waiting before sowing. Germination time not stated; 21 days assumed.

1% germination.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Alnus p. 18Public domain
Show the original text
Alnus (Betulaceae). All samples were received in March, and had already undergone at least 6 m of DS and probably more. Since DS was clearly detrimental in A. rugosa germ. 70L(1%), 40-70D(2%), and 3% in May and June in OT. None germ. in 70D or 70 GA-3.
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Alnus p. 18. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list.

How each step is done, in Deno’s words, and what Verified and Derived mean.

Germination trials

Readers’ own records of sowing this species, published after review. Share your trial · All trials

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