Japanese wisteria

Profile

Family

Fabaceae

Habit

Climber

Height

8.5 m

Spread

9 m

Growth

fast

Lifespan

70 years

First yield

after 12 years

Hardiness

zone 5–9

Shade tolerance

full sun

Soil

Sand, Silt, Loam

Soil moisture

semi-dry – very wet

pH

6 – 7

Synonyms

Blauregen, Wisterie

Flowering & harvest

Times apply to the northern hemisphere in a temperate climate and shift with altitude and cultivar.

Uses

Edible: Samen – gekocht. Im Feuer gebacken schmecken sie ähnlich wie Kastanien. Vorsicht ist geboten, siehe Hinweise zur Toxizität oben auf der Seite. Junge Blätter – gekocht. Die zarten jungen Blätter werden manchmal gegessen und auch als Tee-Ersatz verwendet. Blüten – gekocht. In Teilen Chinas als Nahrungsmittel verwendet.

Medicinal: Traditional Applications (mainly in Japan/China) External Use: Root Bark: For joint pain (as a compress or paste). Antimicrobial properties (against skin infections). Flower Extract: Diluted form for skin cleansing (antibacterial). Internal Use (rare and strictly dosed!): Seeds: In minimal amounts as an emetic (now obsolete!). Caution: Contains Wistarin (toxic lectin) - leads to nausea, vomiting, diarrhea. Modern Research Active Ingredients: Flavonoids (in flowers): Antioxidant. Triterpenoids (in bark): Anti-inflammatory. Potential Applications: Study on Wisteria extracts against certain cancer cells (preclinical, not confirmed). Warnings All parts of the plant are toxic (especially seeds). Symptoms when ingested: Abdominal pain, vomiting, dizziness. No self-medication! Traditional applications require expertise.

Other uses: The bark is used for making ropes and sandals. The branches can be used as cables and for bridge construction, known for their durability. Ropes and sandals are made from the bark, and the wood is also processed. In the Japanese Iya Valley (Tokushima Prefecture), bridges were constructed using the plant's vines to cross rivers. The vines were intertwined once they reached a sufficient length, and wooden planks were added.

Growing

Landscaping: Arbor, trellis, espalier. Prefers good, loamy soil in a sunny south or southwest position, sheltered from cold winds and morning frost [11, 200]. Plants can become chlorotic in alkaline soils [200]. Excessive leaf growth at the expense of flowering is caused by overly nutrient-rich soil [200]. Although hardy to about -20°C [200], they require the additional warmth of a sunny wall to thrive in areas with cool summers [184]. It may take several years for the plants to establish after planting [219], usually due to excessive shade or overly nutrient-rich soil; root restriction can be helpful [219]. A vigorous climbing plant that winds around shrubs and trees but can also thrive as a freestanding shrub up to about 2 meters in height. The shoots twine clockwise [182]. This species is closely related to W. sinensis [50, 126]. Often grown as an ornamental plant, with many named varieties [182, 200]. The flowers emit a strong scent, which can be sweet or musty depending on the variety [249]. Mainly blooms on short shoots. When removing unwanted lateral branches, it is best to prune them back to 2-3 leaves rather than removing them completely, as this promotes the formation of flowering shoots [249]. Heavy pruning is best done in spring, immediately after flowering [249]. The plants tolerate even the most severe pruning and will regrow even if cut back to the base [249]. Self-fertile, typically yielding good seed crops in cultivation. Varieties like "Geisha" and "Royal Purple" are particularly suitable for this purpose [249]. Plants of this genus are particularly susceptible to honey fungus [200]. This species forms a symbiotic relationship with specific soil bacteria, which form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is used by the growing plant itself, while the rest can be utilized by other nearby plants [200]. They also form a symbiotic relationship with a mycorrhizal fungus, providing the plants with more water, phosphorus, and other minerals [249]. Not native to North America, invasive, naturalized, plant is wholly or partially toxic, fragrant flowers, very conspicuous blooms. Information on growth form and root pattern is also helpful for designing polycultures and above-ground architecture (shape - tree, shrub, etc., and size as mentioned above) if available. Woody. Growth form is a single or multi-stemmed vine from a crown [1-2].

Propagation

The seed does not exhibit dormancy and can be sown immediately after ripening in a seedbed, with germination expected in spring. Soak the seeds in warm water for 24 hours and then sow them in early spring in a greenhouse. Alternatively, sow the seeds in a seedbed outdoors in late spring. Germination may occur in the first spring but could be delayed for up to an additional 12 months. Transplant the seedlings into individual pots once they are large enough and continue growing them in a seedbed through the first winter. Plant them out in late spring or early summer. Plants grown from seeds have a slow growth rate, taking up to 20 years to bloom. Take basal cuttings from lateral shoots in early to mid-summer in a frame. Select cuttings with 2-3 leaves once the new growth has hardened, and consider removing a thin strip of bark from the lower 15 mm to expose the cambium for better rooting and lignification. Root the cuttings in a mist bed with soil temperatures of 27-30°C within 4 weeks, and they should develop into well-established plants by autumn. Layering can be done in spring by laying a long shoot on the ground, covering it lightly with soil, and allowing roots to form at intervals along the stem. Once well-rooted, the shoot can be divided into multiple plants, potted, and kept in a slightly shaded area in a greenhouse until established before being planted out as needed.

Origin & habitat

E. Asia - Japan.

Moist land that is often overlooked, along with hedgerows and the edges of woodlands.

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