Plant of the Month for February, 2019

 (Jefferson-ee-a dy-FIL-uh)

General Information:

Jeffersonia diphylla is uncommon both in the wild and in gardens. It starts early in spring with purplish new growth that opens with white flowers long before leaves show on deciduous trees. Unfortunately the flowers only last a few days. Its real beauty comes next as the blue-green leaves develop. The shape of these is very unusual and look as if someone has pasted two leaves together, hence the name diphylla.

Jeffersonia diphylla :photo by Robert Pavlis

This is a very typical shade plant, that grows quick in spring to gather some sun light, and then enjoys as shady, cool summer under deciduous trees. It prefers a moist location, but I grow it in a dry area, that gets full noon day sun, and it seems to enjoy the spot. If it gets too dry it will go underground in late summer, but my plant seems to keep its leaves all summer long.

Jeffersonia diphylla, spring buds :photo by Robert Pavlis

Jeffersonia diphylla, spring buds :photo by Robert Pavlis

Common names include, twinleaf, helmet pod and ground squirrel pea. The name twinleaf obviously refers to the leaves. Helmet pod is a good description of the seed pod, which stick straight up, but is shorter than the leaves. As it dries and releases the seeds, it curves over and starts looking more like a pipe.

effersonia diphylla :photo by Robert Pavlis

Jeffersonia diphylla :photo by Robert Pavlis

There are two species in the genus Jeffersonia, the other being J. dubia, with light lavender blooms.

Jeffersonia diphylla, collecting seed in an organza bag :photo by Robert Pavlis

Jeffersonia diphylla, collecting seed in an organza bag :photo by Robert Pavlis

Jeffersonia diphylla, dry seed showing pipe seed pod :photo by Robert Pavlis

Jeffersonia diphylla, dry seed and pipe-like seed pod :photo by Robert Pavlis

Jeffersonia seeds are hydrophilic and the embryo will die if seed dries out. Sowing the seeds before any drying takes place is the best approach.  However, if they are to undergo a period of storage, they are first allowed to dry a bit and then are sealed in a plastic bag in slightly moist vermiculite.

Life Cycle: perennial

Height: 45cm (18in)

Bloom Time: early spring

Natural Range: Eastern North America

Habitat: damp woodlands

Synonyms:  none

 

Cultivation:

Light: part to full deciduous shade

Soil: rich organic soil, limestone

Water: moist to medium

USDA Hardiness Zone: (4?) 5 - 8

Propagation: seed, division

Seedex availability (ORG&HPS annual Seed Exchange): occasionally

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Sow immediately. The viability of these seeds is short or the species propagates best with fresh seed. Stored seed might be coaxed into germination with temperature cycling and patience.

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This species needs special care as described.

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Sow @ 20°C for 6 weeks, then place @ 4°C for 6 weeks, then slowly raise temperature to 10°C for 6 weeks. If there is no germination, repeat the cycle. This mimics fall sowing outdoors for spring germination.
Jeffersonia seeds are hydrophilic and the embryo will die if seed dries out. Sowing the seeds before any drying occurs is the best approach. However, if they are to undergo a period of storage, they are first allowed to dry a bit and then are sealed in a plastic bag in slightly moist vermiculite. Expect germination while in cold cycle. Research by Jeffery and Carol Baskin demonstrated "Freshly-matured seeds of ... Jeffersonia diphylla .....have underdeveloped (ca. 0.6 mm in length) embryos and exhibit deep, simple morphophysiological dormancy (MPD). For rapid growth of the embryos at October (20°/10° C) and November (15°/6° C) temperatures in October and November, seeds must first be exposed to high (30°/15°C) summer temperatures. If embryo growth is not completed in autumn, it continues during winter. However, even after 10-12 weeks at summer temperatures, embryos grew very little at 5°C, unless growth already had begun at autumn temperatures. After embryo growth has been completed, or after it has been initiated, seeds require cold stratification (5°C) to overcome dormancy. Embryos must attain a minimum length of about 1 mm before seed dormancy can be broken by cold stratification. Gibberellic acid increased the rate of embryo growth in seeds kept at 20°C, but only 1-9% of them germinated. Thus, GA substitutes for warm but not cold stratification. High summer temperatures, as well as the traditionally-used autumn and winter temperatures, should be used in germinating seeds with deep, simple MPD."
Robert Pavlis