Sosnowsky's hogweed

Botanical data

Family

Apiaceae (Apiaceae)

Height

2–4 m

Width

1.5–2.5 m

Habit

Upright

Growth rate

Fast

Position

Full sun, Partial shade

Soil

Humus-rich, Loamy

pH reaction

pH 5.5–7.5

Moisture

Moist

Bloom

June–August

Hardiness

USDA 3a–8b

Propagation

From seed

Characteristics

A colossal umbellifer of umbrella-like habit, 2–4 m tall (record 5 m), with a single straight, hollow stem as thick as an adult's arm (4–10 cm across). The defining stem feature is dark red or purple blotches and streaks on a light-green ground plus rough, stiff hairs. Leaves are huge — up to 1.5 m long, deeply palmately-pinnately divided into 3–7 large, cut segments, light green, matte, on long fleshy stalks; they grow in a rosette from the ground and alternately along the stem. The inflorescence is a gigantic, flat compound umbel 30–80 cm across (record up to 1 m), made of 30–75 rays each ending in a small umbellet with tiny white flowers. Blooms from June to August in its second or third year of life and DIES after seed set (hapaxanthic — flowers only once in its life). Fruits are flat, oval schizocarps, up to 8,000 per plant, viable in the soil for 5–10 years. The whole plant contains FURANOCOUMARINS — compounds that trigger a phototoxic skin reaction on UV contact. Sosnowsky's hogweed is practically identical with the closely related giant hogweed (Heracleum mantegazzianum) — botanical differences are subtle, impractical in the field. In practice both are treated JOINTLY as „giant hogweed”.

Growing and care

Companion plants

The evidence level indicates whether the relationship is backed by research, observation, or gardening tradition.

Toxicity

History and origin

The species was scientifically described in 1944 by the Soviet botanist Ida Mandenova and named in honour of her supervisor, Dmitry Sosnowsky — a Caucasian flora researcher. Its expansion beyond the native Caucasus began in the 1950s, when Soviet agrotechnicians identified it as a promising fodder plant: enormous green mass yield per hectare, fast growth, cold-hardiness. In subsequent years it was mass-planted in Russia, Belarus, Ukraine, the Baltic states and Poland, cultivated as cattle feed and an industrial raw material. The experiment failed on both counts: cattle refused to eat the plant (strong smell, bitterness from essential oils, deterrent cues), while mass burns among farm workers began to be recorded. In the 1980s and 1990s cultivation was gradually shut down, but seeds remained in the soil for decades, and plants on abandoned fields began to expand along rivers, ditches and roadsides. Since 2016 Sosnowsky's hogweed has been on the EU list of invasive species of Union concern (Regulation EU 1143/2014); in Poland the landowner has a legal duty to control it. Today it is one of the symbols of failed 20th-century agronomic experiments and simultaneously one of the more serious public health problems in Poland and Ukraine.

Uses

Sosnowsky's hogweed has NO horticultural, culinary or medicinal use — the „application” field in a cultivation context makes no sense, because the plant is banned from planting in Poland and the EU and subject to a control duty. Historically used as cattle fodder (USSR experiment of the 1950s, failed) and there were attempts to extract essential oils — both paths were abandoned. Today contact with the plant serves EXCLUSIVELY its CONTROL. The landowner where the hogweed has grown has a legal duty to remove it — best by digging up with the taproot before flowering, in full protective gear, on an overcast day. Full procedures, recognition (contrast with native umbellifers), personal protection and post-contact procedures for skin or eye — in a separate [guide about hogweed](/en/guide/barszcz-sosnowskiego-jak-rozpoznac/). Stands of more than a few specimens report to the relevant authority (RDOŚ in PL, Umweltamt in DE, Fachstelle Neobiota in CH, local council in UK) — they have programmes and budget for professional control.

Trivia

• The specific name „sosnowskyi” commemorates Dmitry Sosnowsky (1885–1953) — a Georgian-Russian botanist studying the Caucasus flora; described in 1944 by his student Ida Mandenova.
• The plant is HAPAXANTHIC — flowers only ONCE in its life (in the second or third year), dying after seed set. One specimen can produce up to 8,000 seeds viable in the soil for 5–10 years.
• In the 1950s and 60s in Poland, Sosnowsky's hogweed was cultivated under the name „Caucasian hogweed” as a promising cattle fodder; brochures advertising its high yields have survived in agronomic archives.
• Almost identical in appearance is the closely related giant hogweed (Heracleum mantegazzianum) — in Germany, Switzerland and Britain this second form dominates; both form one problem called „giant hogweed” in English.

Frequently asked questions