Invasive Species

Question 1

Can you name any invasive species?

Answer 1

Knotweed
Himalayan Balsam
Hogweed

Question 2

How would you identify knotweed?

Answer 2

Spring:
- Shoots in spring: asparagus spears - red/ purple in colour
- Stems grow longer and resemble bamboo
- Emerging leaves form a zig zag on the stem
- Forms dense thickets known as stands

Summer:
- Shovel shaped bright green leaves forming a dense canopy - point on the tips of each leaf
- Leaves up to 200mm long
- Canes 3- 3.5m long forming a dense stand
- Clusters of creamy white elongated flowers

Autumn:
- Leaves are yellow/ orange
- Leaves brittle and wilt in sept/ Oct
- Stems turn brown

Winter:

• No leaves
• Brown stems which are upright

Roots:
- Fresh roots will snap like a carrot and are brown on the outside and orange/ yellow on the inside

Question 3

What legislation applies to invasive species?

Answer 3

Wildlife and Countryside Act 1981

Question 4

What are the issues with Japanese Knotweed?

Answer 4

• Very fast growth -
• Roots (rhizomes) spread at depths up to 2m deep and 7m horizontally

Question 5

Tell me about the rhizomes of Japanese Knotweed

Answer 5

• Rhizomes are like underground stems
• Rhizomes can snap easily, similar to a carrot
• External part of rhizome is dark brown, the internal is orange/ yellow
• Even a small part of root can form a whole new plant

Question 6

Tell me bout knotweed stems

Answer 6

• Like bamboo
• Distinctive purple speckles
• green leaves spout

Question 7

Characteristics of hogweed

Answer 7

c. 2-5m
The leaves are incised and deeply lobed.
Leaves can be up to 1-1.5m
stout, bright green stem with extensive dark reddish-purple splotches and prominent coarse white hairs, especially at the base of the leaf stalk
Hollow, ridged stems are 3–8 cm (1–3 in) in diameter, occasionally up to 10 cm (4 in) in diameter, and can grow to more than 4 m (13 ft) high.