Deno’s Garden

Jeffersonia diphylla

Twinleaf · Blue Twinleaf · Ground Squirrel Pea · Helmet Pod · Rheumatism Root · Manchuria

Family BerberidaceaeGenus Jeffersonia

White flowers on bare stalks above paired kidney-shaped leaves
FlowerKrzysztof Ziarnek, KenraizCC BY-SA 4.0

About the plant

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

The plant

Habit
Herbaceous perennialPlant Finder
Habit
Perennial, Forb/herbPLANTS Database
Height
0.75-1.5 ftPlant Finder
Spread
0.5-0.75 ftPlant Finder
Flower
Showy; whitePlant Finder
Blooms
AprilPlant Finder
Native range
North AmericaGBIF Backbone Taxonomy
Native range
Eastern North AmericaPlant Finder
Native range
Canada, lower 48 statesPLANTS Database
Hardiness zones
5-7Plant Finder
Note
Germination is hypogeal; about half the seedlings lose the radicle to rot before a leaf appears.Seed Germination Theory and Practice, 2nd ed.
Note
Tolerates heavy shade. Susceptible to slugs and snails.Plant Finder

Growing conditions

Sun
Part shade
Soil
Moist, humusy, well-drained, limestone
Watering
Medium

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

Sources: Plant Finder — Missouri Botanical Garden; PLANTS Database — USDA NRCS; GBIF Backbone Taxonomy — Global Biodiversity Information Facility; Seed Germination Theory and Practice, 2nd ed. — N. C. Deno.

This source reports 5 treatments. All are shown.

Protocol 1

DerivedN. C. Deno, 1993

Difficulty High Rated by us, not by the source.

Start around October 19, 2026 for a May 3 last frost. Too late for spring 2027 — that needed starting on October 18, 2025.

  1. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    Deno gives no cycle lengths here; three months is his standard cycle.

  2. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

  3. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  4. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    5% here, and nothing before it.

  5. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  6. Warm moist stratification

    Temperature: 70°F 21°C

about 15 months from start to sowing. Then 84 days to germinate.

63% germination in 14–84 days.

The best run Deno got, and the one to copy: nothing for four cycles, then most of the packet.

This source doesn't state how long.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, JeffersoniaPublic domain
Show the original text
Jeffersonia (Berberidaceae). For the two species studied, DS is fatal with only a few percent surviving DS 6 m 40 and none surviving DS 6 m 70. Some of the fresh seeds rot quickly after contacting moisture and these are internally infected. J. diphylla seeds collected in June 1987 germ. 70-40(4%)-70(8%)-40(34%)-70(12%)-40-70(4%)-40-70(2%) and 40-70-40(2%)-70(34%)-40(24%)-70(8%). Seeds collected in June 1988 germ. 70(none over six cycles) and 40-70-40-70(5%)-40-70(63% in 2-12w). Seeds collected in 1990 were all internally infected and soon rotted. In view of the results with J. dubia, it is likely that outdoor treatment would have been effective. Germination is hypogeal and begins with development of a tour inch radicle. The single true leaf may emerge as soon as the 3rd w after radicle emergence or it may take another cycle or two. About half of the seedlings ultimately have the radicle rot and the seedling die before any leaf development.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Jeffersonia. 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, 1993

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

Start around March 21, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on March 20, 2026.

  1. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    Deno gives no cycle lengths here; three months is his standard cycle.

  2. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    4% in the first cold period.

  3. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    A further 8%.

  4. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    34% -- the largest flush.

  5. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    A further 12%.

  6. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  7. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    A further 4%.

  8. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  9. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    A last 2%.

Steps after step 4 run on after germination.

about 12 months from start to sowing. Germination time not stated; 21 days assumed.

34% germination.

4, 8, 34, 12, 4 and 2 per cent across nine cycles -- two thirds of the seed, over two years.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, JeffersoniaPublic domain
Show the original text
Jeffersonia (Berberidaceae). For the two species studied, DS is fatal with only a few percent surviving DS 6 m 40 and none surviving DS 6 m 70. Some of the fresh seeds rot quickly after contacting moisture and these are internally infected. J. diphylla seeds collected in June 1987 germ. 70-40(4%)-70(8%)-40(34%)-70(12%)-40-70(4%)-40-70(2%) and 40-70-40(2%)-70(34%)-40(24%)-70(8%). Seeds collected in June 1988 germ. 70(none over six cycles) and 40-70-40-70(5%)-40-70(63% in 2-12w). Seeds collected in 1990 were all internally infected and soon rotted. In view of the results with J. dubia, it is likely that outdoor treatment would have been effective. Germination is hypogeal and begins with development of a tour inch radicle. The single true leaf may emerge as soon as the 3rd w after radicle emergence or it may take another cycle or two. About half of the seedlings ultimately have the radicle rot and the seedling die before any leaf development.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Jeffersonia. 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, 1993

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

Start around March 21, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on March 20, 2026.

  1. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    Deno gives no cycle lengths here; three months is his standard cycle.

  2. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

  3. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    2% in the second cold period.

  4. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    34% -- the largest flush.

  5. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    A further 24%.

  6. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    A last 8%.

Steps after step 4 run on after germination.

about 12 months from start to sowing. Germination time not stated; 21 days assumed.

34% germination.

The same 1987 seed the other way round: 2, 34, 24 and 8 per cent, two thirds in all.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, JeffersoniaPublic domain
Show the original text
Jeffersonia (Berberidaceae). For the two species studied, DS is fatal with only a few percent surviving DS 6 m 40 and none surviving DS 6 m 70. Some of the fresh seeds rot quickly after contacting moisture and these are internally infected. J. diphylla seeds collected in June 1987 germ. 70-40(4%)-70(8%)-40(34%)-70(12%)-40-70(4%)-40-70(2%) and 40-70-40(2%)-70(34%)-40(24%)-70(8%). Seeds collected in June 1988 germ. 70(none over six cycles) and 40-70-40-70(5%)-40-70(63% in 2-12w). Seeds collected in 1990 were all internally infected and soon rotted. In view of the results with J. dubia, it is likely that outdoor treatment would have been effective. Germination is hypogeal and begins with development of a tour inch radicle. The single true leaf may emerge as soon as the 3rd w after radicle emergence or it may take another cycle or two. About half of the seedlings ultimately have the radicle rot and the seedling die before any leaf development.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Jeffersonia. 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 4

DerivedN. C. Deno, 1993

  1. Sow and cover

    Temperature: 70°F 21°C

    Nothing over six cycles.

No stated waiting before sowing.

0% germination.

Starting warm got nothing at all from the 1988 seed. Start cold instead.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, JeffersoniaPublic domain
Show the original text
Jeffersonia (Berberidaceae). For the two species studied, DS is fatal with only a few percent surviving DS 6 m 40 and none surviving DS 6 m 70. Some of the fresh seeds rot quickly after contacting moisture and these are internally infected. J. diphylla seeds collected in June 1987 germ. 70-40(4%)-70(8%)-40(34%)-70(12%)-40-70(4%)-40-70(2%) and 40-70-40(2%)-70(34%)-40(24%)-70(8%). Seeds collected in June 1988 germ. 70(none over six cycles) and 40-70-40-70(5%)-40-70(63% in 2-12w). Seeds collected in 1990 were all internally infected and soon rotted. In view of the results with J. dubia, it is likely that outdoor treatment would have been effective. Germination is hypogeal and begins with development of a tour inch radicle. The single true leaf may emerge as soon as the 3rd w after radicle emergence or it may take another cycle or two. About half of the seedlings ultimately have the radicle rot and the seedling die before any leaf development.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Jeffersonia. Quoted exactly. Every value on this card comes from this record; the step names come from a fixed list.

Protocol 5

DerivedN. C. Deno, 1993

  1. Dry storage

    Duration: 180 daysTemperature: 70°F 21°C

  2. Sow and cover

    None survived the dry storage.

about 6 months from start to sowing.

0% germination.

Dry storage is fatal. Six months at 40 left a few per cent alive; six months at 70 left none.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, JeffersoniaPublic domain
Show the original text
Jeffersonia (Berberidaceae). For the two species studied, DS is fatal with only a few percent surviving DS 6 m 40 and none surviving DS 6 m 70. Some of the fresh seeds rot quickly after contacting moisture and these are internally infected. J. diphylla seeds collected in June 1987 germ. 70-40(4%)-70(8%)-40(34%)-70(12%)-40-70(4%)-40-70(2%) and 40-70-40(2%)-70(34%)-40(24%)-70(8%). Seeds collected in June 1988 germ. 70(none over six cycles) and 40-70-40-70(5%)-40-70(63% in 2-12w). Seeds collected in 1990 were all internally infected and soon rotted. In view of the results with J. dubia, it is likely that outdoor treatment would have been effective. Germination is hypogeal and begins with development of a tour inch radicle. The single true leaf may emerge as soon as the 3rd w after radicle emergence or it may take another cycle or two. About half of the seedlings ultimately have the radicle rot and the seedling die before any leaf development.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Jeffersonia. Quoted exactly. Every value on this card comes from this record; the step names come from a fixed list.