Invasive Plants on the Ridge
Introduction
This booklet was an Eagle Scout project by Emily Carr, from Troop 12G. This booklet covers 5 different invasive species in Paradise, and surrounding communities. The origin, identification, life cycle, removal methods, and even fun facts are included. All sources can be found at the back of the booklet. It is very important to remove these species properly to prevent them from growing back or spreading. These species have taken over the beautiful, native plants in our area, and are posing a fire hazard. With your help, we can fight these plants and make room for our natural, beautiful town.
Brooms
OIdentification
igin
nch broom (Genista nspessulana), Scotch broom isus scoparius) and Spanish om (Spartium junceum), unlike r name suggests, all originated in Mediterranean. All three were ught over to the US as ornamentals in the mid 1800’s.
French broom is an evergreen shrub, and can grow 6-10 feet tall. Young stems are green with 8-10 ridges, and are covered with silvery hairs. The leaves are compound, with 3 leaflets each, and roughly ½-¾ of an inch. The pea-shaped yellow flowers develop at the end of branches. Their seed pods are about 1 inch, and are entirely covered in hairs.
Scotch broom, while similar to the French variety, is a deciduous shrub. This also grows 8-10 feet. Young branches are dark green with single leaves. Older branches have compound leaves with 3 leaflets each. Scotch broom stems have 5 ridges, which are hairy. They have similar peashaped yellow flowers that grow either individually, or in pairs. These seed pods can be ¾ of an inch, to 2 inches long, with hairs only along the margin. 1.
Brooms
Identification
Spanish broom is very different from the other two varieties. Their leaves are singular, with no leaflets. These have round stems with bigger, yellow flowers. Seed pods have little to no hairs. Spanish broom flowers have a very strong, sweet fragrance.
Life Cycle
The broom's flowers bloom from April through June. They produce seed pods from mid to late summer. Seed pods dry out in the hot months and explode open, spreading the seeds. They are slow to grow for the first two years, then growth rapidly speeds up. After the first two years they can grow 3 to 4 feet per year. Plants can live 12-17 years, but with good conditions some can live up to 25 years.
2. *All images from the Brooms section are of Scotch Broom
Brooms
Is it Harmful?
All of these species are harmful to humans and possibly pets if ingested.
How to Remove It
Mechanical removal, goats, and controlled burning are all methods this plant can be removed. Cutting can lead to resprouts, promote growth by making room for more plants, and can spread seeds if done with large equipment.
Fun Facts
There are reports of horses ingesting brooms causing neurological effects, including muscle and balance issues, and excitement. Broom seeds can be dormant for decades.
Starthistle
Origin
Yellow starthistle (Centaurea solstitialis) is native to Eurasia. Its seeds were accidentally brought to California in a shipment of alfalfa seeds from South America around 1850.
Identification
Yellow Starthistle, as the name implies, has yellow flowers. On the receptacles of the flowers (base of the flower) there are several long, woody thorns. The stems and leaves are a pale green due to a white fuzz that covers the plant.
Life Cycle
With this winter annual, the majority of its seedlings germinate in fall. It blooms in the spring, and in the summer it completes its cycle. Due to its shape, the seeds do not spread very far past the parent plant, typically within two feet.
Starthistle
Is it Harmful?
Due to its spiky nature, yellow starthistle restricts activity, and can cause great pain to humans and pets. It is toxic to horses.
How to Remove
Mechanical removal (pulling) is an option. Cutting can be effective if cut before the plant flowers, or if done so where no leaves remain under the cut. Grazing is another effective option.
Fun Facts
Starthistle has two types of seeds. The first type is a small acorn-shaped seed, and the second type is a similarly shaped seed, but with long white tufts at the end. By having two different types of seeds, it increases its chances to reproduce.
Tree of Heaven Origin
The tree of heaven (Ailanthus altissima), originally from China, was brought to Philadelphia in 1784. It was introduced to California in the 1840’s by Chinese immigrants during the Gold Rush. The tree was used as an ornamental, and also for shade.
Identification/Life Cycle
The most common way to identify a tree of heaven is by its foul smell. Its leaves have 11 or more pointed leaflets, with 2-4 teeth at the base. Its seeds are winged-shaped. They look similar to maple seeds, though they come as single seeds. As they mature, the seeds turn a reddish color. They are often clustered in large groups. During winter, it is very easy to identify a tree of heaven based on the leaf scars on its bark. When its leaves fall off, they leave leaf scars that are heart-shaped. To reproduce, seeds from the tree of heaven are dispersed by wind. Once planted, the tree will grow and spread by sending up root suckers. The trees grow up to 10 or 15 feet tall in about a year when they mature. It has tiny yellow-greenish flowers that are clumped together like the seeds. They bloom from April through May.
Tree of Heaven
Is it Harmful?
Though nontoxic to humans, the high amount of pollen that the tree of heaven produces triggers allergies in many people. A few cases of dermatitis have been reported to be a result of touching the tree.
How to Remove
Trees may be killed by girdling about 6 inches above the ground. This may result in regrowth from the root ball. Young trees can be pulled up, though this only works if all of the roots have been pulled as well. Remaining roots can resprout. Simply cutting the trees may result in dozens of new sprouts, and often makes the issue worse. Goats and prescribed burns are not an effective option for this reason.
Fun Facts
Tree of heaven is popular in natural medicines.
T.
Himalayan Blackberry
Origin
Himalayan blackberry (Rubus armeniacus), was brought to the east coast from Eurasia in 1885 for berry production. It was established in California by 1945.
Identification
Himalayan blackberries have thick, arching stems (called canes), with strong thorns. Leaves are in groups of 3 or 5 leaflets with toothed edges. The leaf undersurfaces are pale green to whitish, with thorns along the midrib. Canes can reach 10 feet high, and nearly 40 feet long.
Life Cycle
The Himalayan blackberry disperses its seeds through animal digestion, and matures in about 1-2 years. It can form dense, impassable stands, with aggressive growth in the spring. The canes can form roots where they touch the ground. This plant flowers from July to September, with fruit following.
Himalayan Blackberry
Is it Harmful?
The fruit of Himalayan blackberry is not harmful, and is a favorite summertime berry. However, its strong thorns can cause painful puncture wounds.
How to Remove
Established stands can be difficult to eradicate. Mechanical removal of the root ball is recommended, as cutting alone will not kill the plant. Immediate removal is recommended if an undesired plant pops up. Goats are also a good control method.
Fun Facts
First year stems do not flower, and are called primocanes. They can grow 2-3 inches per day.
Blackberry
Pokeweed
Origin
Common pokeweed (Phytolacca americana) is native to the eastern states of America. There is no definite year or time period in which it came to California.
Identification
Pokeweed is an unpleasant smelling fleshy plant, with purple stems that can grow up to 10 feet tall. The flowers are magenta, with white petals that grow in clumps. Pokeweed berries are a glossy purple and black color. They grow on long stocks. While they are fatally toxic to humans and livestock, birds enjoy them.
Life Cycle
Pokeweed seeds are primarily spread through birds. It is a perennial, meaning it lives longer than two years, and matures quickly. Although it is a perennial, in our area the cold winters cause pokeweed to die back completely. It blooms through July and August. 10.
Pokeweed
s it Harmful?
Pokeweed is fatally toxic to humans nd livestock, every part of the plant s toxic and it should be treated arefully.
How to Remove
Mechanical removal of small plants can be done by hand, but larger plants should be cut. Cutting should be done below the root crown, and cultivation should take place before fruits mature to avoid seedlings coming back the following year. Grazing is not a valid option, as the plants could kill the livestock used. If products are used, it should be applied postemergence, when plants are growing rapidly, applications in spring provide the best control.
Fun Facts
Even though mature plants are toxic, young plants can be eaten if cooked properly. They are a delicacy on the East Coast, and were once canned and sold.
Pokeweed
How to Help
Special Thanks To:
Troop 12 and Troop 316 for doing the research
Faith Lutheran Church for letting us use their space
All the generous donors including:
The Rotary Club of Paradise California
AND MOST IMPORTANTLY
Paradise Parks and Recreation Department for making this project possible
Sp. Thanks
Brooms
(1)https://www.nwcb.wa.gov/weeds/spanish-broom
(2)https://www.fs.usda.gov/database/feis/plants/shrub/genmo n/all.html
(3)https://www.fs.usda.gov/database/feis/plants/shrub/spajun /all.html
Yellow Star-Thistle
(1)https://catalog.extension.oregonstate.edu
(2)https://agriculture.vic.gov.au
(3)https://www.fs.usda.gov
(4)https://ipm.ucanr.edu/PMG/PESTNOTES/pn7402.html
Tree of Heaven
(1)https://www.nature.org/en-us/about-us/where-wework/united-states/indiana/stories-in-indiana/journeywith-nature--tree-of-heaven/
(1)https://www.nature.org/en-us/about-us/where-wework/united-states/indiana/stories-in-indiana/journeywith-nature--tree-of-heaven/
(3)https://extension.psu.edu/tree-of-heaven
Himalayan Blackberry
(1)https://www.nps.gov/lavo/learn/nature/himalayanblackberry.htm#:~:text=Flowering%20extends%20from %20early%20July,1885%20as%20a%20cultivated%20c rop.
(2)https://www.cal-ipc.org/plants/profile/rubusarmeniacus-profile/
(3)https://www.fs.usda.gov/database/feis/plants/shrub/ru bspp/all.html
(4)https://www.calipc.org/resources/library/publications/ipcw/report71/
(5)https://www.nwcb.wa.gov/images/weeds/Rubu armenia cus.pdf
Pokeweed
(1)https://www.cal-ipc.org/plants/profile/phytolaccaamericana-profile/
(2)https://www.fs.usda.gov/wildflowers/plant-of-theweek/phytolacca americana.shtml
(3)https://ipm.ucanr.edu/PMG/PESTNOTES/pn74173.ht ml
(4)https://goldengategarden.typepad.com/golden_gate _gardener_/2017/11/pokeweed-a-huge-and-toxicweed.html
Created By Emily Carr
2023 Eagle Scout Project Troop 12G, Chico