Poison Hemlock
Lesson 1: Introduction to Poison Hemlock
Objective: Students will understand the characteristics of Poison Hemlock
Students will need: construction paper 12”x18”, glue, crayons or colored pencils, poison hemlock
coloring sheet, poison hemlock identification sheet.
Vocabulary:
noxious – harmful to the body
herbaceous – a plant with a non-woody stem that dies down to the soil level.
biennial - appearing every two years.
herbicide – a substance known to kill plants
Say, “Imagine taking a walk down the side of a country road and coming across a plant with tiny white flowers.”
Ask, “How many of you have ever picked flowers for your mom or grandma?”(Let students respond)
Say “This sounds pretty typical and normally you would not think anything of it. (Show photo of grazing cows)
Say “There is a large plant in our state that bears tiny white flowers. But DO NOT touch this plant”
Say, “The name of the plant is called Poison Hemlock.” (Show photo of Poison Hemlock)
Poison Hemlock is: (Discuss each of the these concepts with the students)
 The leaves on the plant resemble that of parsley (Compare picture of Poison Hemlock and parsley)
 Purple striping up and down the stem
 Root is white and resembles a parsnip
 Can grow up to approximately 12 feet tall
Say “Poison Hemlock can be found in several places in the state of Idaho. Poison Hemlock can be found in
poorly drained soil such as ditches, streams and other surface water.
Say, “The Idaho Sate Department of Agriculture Treasure Valley County Weed Superintendant is asking for your
help in controlling the growth and spread of this plant. Learn what the plant looks like to be able to identify it
easily.”
Activity 1:
Pass out coloring sheet of Poison Hemlock and have the students color/trace the leaves according to the description given during the
class discussion.
Fold construction paper in half to make a folder. Glue colored picture of Poison Hemlock plant to cover of folder. Put name on cover.
this folder will be used to keep information given during this unit.
Activity 2: Give each student a copy of the information sheet of poison hemlock. Have the fill in the blanks with the correct information
from the text.
Activity 3:
Give each student a copy of the characteristic sheet of Poison Hemlock. Have the students circle the pictures that help identify a
poison hemlock plant.
(Background information for teacher)
WHAT IS Poison Hemlock?
Poison Hemlock is known for its poison. It is a herbaceous biennial plant which grows between 6-12 feet tall, with a smooth green
stem, usually spotted or streaked with red or purple on the lower half of the stem. The leaves are very small and lacy, overall triangular
in shape, up to 20 inches long and 15 inches wide. The flowers are small, white, clustered in umbels up to 4-6 inches across. The plant
is often mistaken for fennel, parsley or wild carrot although the characteristic stem hairs of the wild carrots are missing. The Poison
Hemlock root is fleshy, white and often unbranched and can be mistaken for parsnip. When crushed, the leaves and root emit a rank,
unpleasant odour often compared to that of a mouse or parsnips.
Poison Hemlock contains the alkaloids Coniine, N-methylconiine, conhydrine, pseudoconhydrine, g-coniceïne and Atropine . The most
important and toxic of these is Coniine. Coniine is a neurotoxin, which disrupts the workings of the central nervous system and is toxic
to people and all classes of livestock.
Poison Hemlock has been introduced and naturalised in many other areas, including much of Asia, North America and Australia.
Poison hemlock is often found on poorly drained soils, particularly near streams, ditches, and other surface water.
For video of poison hemlock see also:
http://www.idahoweedawareness.com/vfg/vfgmap/region2/phemlock1/phemlock1.html
Additional information
The Enemy - Poison hemlock (Conium maculatum) is a biennial plant that grows up to 12 foot tall. This is the most toxic of Idaho's 57
listed noxious weeds. All parts of this plant are poisonous to livestock and humans, in fact the extract of this plant was use to execute
Socrates of ancient Greece. The plant hosts white flowers (don’t mistake this plant for wild parsley). This plant is easy to distinguish as
the stems have a purple striping up and down them that the other plants do. The leaves are fern-like and pinnately divided. The thick
white taproot, which when sliced onto resembles walls with hollow chambers.
How can you identify it? Look closely at the stem of any plant you may suspect of being poison hemlock. The stem is hollow, smooth
(not hairy) and marked with purple streaks and blotches. These blotches and streaks on a green hollow hairless stem, and the mottled
purple spots, are definite identifiers of the plant. The finely divided leaves, fern-like, resemble Queen Anne's lace. Flowers are lacy and
white, appearing from late May to August.
Poison hemlock is a biennial. It grows from seeds. During the first year, it produces a rosette of fern-like leaves close to the ground. The
second season it bolts to form the tall, erect, flowering stems which can be from 4 to 8 feet tall. The white flowers develop into green,
ridged seed capsules which turn brown when the seeds mature. The leaves and flowers smell distinctive, a "mousey" odor.
Name ______________________
WHAT IS POISON HEMLOCK?
Poison Hemlock is a plant that is known for its harmfulness to both humans and many
animals. It is plant that can grow up to 10 feet tall. It takes two growing seasons for
poison hemlock to grow to its fullest. This is known as being biennial. The stem of the
plant is smooth and its color is green with red or purple streaks on the outside. The
green leaves are small and have a lacey appearance in grow together in the shape of
a triangle. The flowers grow in tiny clusters. The plant looks like parsley or wild carrot.
The root of the poison hemlock is white and is often a single unbranched root. It is
often mistaken for a parsnip. When the root and leaves are crushed it gives off a very
bad smell.
Read the above selection and fill in the blanks below.
1. Poison Hemlock is harmful to both ___________________ and ____________________.
2. Poison Hemlock can grow as tall as _______ feet high.
3. The stem of the poison hemlock is green and smooth and has ______________ streaks.
4. The poison hemlock plant looks much like __________________ or wild carrot.
5. The ___________ of the poison hemlock is often single and unbranched.
6. The poison hemlock root is often mistaken for ________________.
7. The root and leaves of the poison hemlock give off a bad ____________________.
WHAT IS POISON HEMLOCK?
(Answers)
Poison Hemlock is a plant that is known for its harmfulness to both humans and many
animals. It is plant that can grow up to 10 feet tall. It takes two growing seasons for
poison hemlock to grow to its fullest. This is known as being biennial. The stem of the
plant is smooth and its color is green with red or purple streaks on the outside. The
green leaves are small and have a lacey appearance in grow together in the shape of
a triangle. The flowers grow in tiny clusters. The plant looks like parsley or wild carrot.
The root of the poison hemlock is white and is often a single unbranched root. It is
often mistaken for a parsnip. When the root and leaves are crushed it gives off a very
bad smell.
Read the above selection and fill in the blanks below.
8. Poison Hemlock is harmful to both __humans_____ and __many animals___________.
9. Poison Hemlock can grow as tall as __ten_____ feet high.
10. The stem of the poison hemlock is green and smooth and has _red or purple__ streaks.
11. The poison hemlock plant looks much like __parsley__________ or wild carrot.
12. The __root______ of the poison hemlock is often single and unbranched.
13. The poison hemlock root is often mistaken for a __parsnip__________.
14. The root and leaves of the poison hemlock give off a bad ____odor__________.
Name_______________________________
Circle the picture that could be used to describe Poison Hemlock.