French Broom (Genista Monspessulana) Technical Report

Genista Monspessulana, commonly known as French Broom, is a Class A weed located on the western coast of the United States. Its appearance is that of a large shrub with yellow, pea-like flowers and small oval leaves in groups of three. It is commonly under 3 meters tall. Its stems are erect, dense, and green or brown densely covered with silky, silvery hairs (U.S.F.S. 2014). It is typically leafy with leaflets ranging from 10mm to 20 mm long and petioles about 5 mm long(U.S.F.S. 2014). There are normally 4 to 10 pea-like flowers about 5mm to 7 mm long on axillary pedicels 1mm to 3 mm long (U.S.F.S. 2014). The fruit is a legume ranging from 15mm to 25 mm long and 5 mm wide with 3 to 8 seeds per pod (U.S.F.S. 2014). French broom seeds are round and generally have elaiosomes attached to them.
French Broom is an angiosperm and its flower has four main parts, the sepals, the petals, the stamen or male part, and the pistil or female part (Reece et al. 2014). In order for fertilization to occur insects or other animals must transport the pollen from the stamen to the pistil (Lambers 2014). An angiosperm ovule, located in the pistil, contains an egg cell and a diploid fusion nucleus, when pollen comes into contact with the top of the pistil it sends it down into the ovary at the pistil's base (Lambers 2014). As the pollen penetrates the ovule, it releases two sperm cells, one fuses with the egg to create a diploid zygote, while the other joins with the fusion nucleus to form a triploid nucleus (Lambers 2014). This triploid nucleus turns into an endosperm, which nourishes the developing embryo, the ovule then undergoes mitosis and becomes a seed, encasing the embryo and endosperm (Lambers 2014). Primary growth in angiosperms occurs as the seed begins to germinate and roots spread into the ground while shoots spread out above ground towards the sky. As the plant develops, the ends of the roots and shoots create mitosis cell division as new cells extend the plants length (Reece et al. 2014).
French broom can invade a wide range of habitats including roadsides, fields, logged areas, bluffs, coastal areas and French Broom is well-adapted to open, sunny, and well-drained sites. French broom can alter the nitrogen level in soil and thereby disrupt low-nutrient ecosystems such as the Puget Sound prairies here in Washington (King County 2014). French broom can also interfere with re-forestation and can aid the spread of wildfires (King County 2014). French broom plants can survive cutting and tend to re-sprout from the crown when cut or burned (King County 2014). Seeds are produced in hard, dry legume pods that burst open when mature and are generally dispersed close to the parent plant unless soil is moved through erosion, flooding, man-made machines, or other means such as animals grabbing and moving them (King County 2014). French broom seeds are hard and long-lived and the plant can produce over 8000 seeds a year (King County 2014). High seed production and long-lived seeds make eradication of established populations very difficult.
For controlling the growth and spread of French Broom, cutting and burning alone have proven to be unsuccessful. However, these approaches combined with the use of an herbicide has proven to yield favorable results. These methods include cutting them from the ground and spraying their stems with herbicide to prevent regeneration (U.S.F.S. 2014). Also, for controlling larger patches, burning them followed by spraying the entire area with an herbicide has been effective (U.S.F.S. 2014). For a single plant, pulling them up from the ground, preferably when they are young, is best (U.S.F.S. 2014).
References Cited
King County. "Noxious Weeds." French Broom Identification, Biology and Control. King County, Washington. Web. 13 Oct. 2014. http://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds/weed-identification/french-broom.aspx
Lambers, Hans. "Plant Reproductive System." Encyclopedia Britannica Online. Encyclopedia Britannica. Web. 13 Oct. 2014. http://www.britannica.com/EBchecked/topic/498651/plant-reproductive-system/76173/Seed-plants
Reece, J., Urry, L., Cain, M., Wasserman, S., Minorsky, P., & Jackson, R. (2014). Campbell Biology. Glenview, IL: Pearson Education, Inc.
U.S.F.S. "Species: Genista Monspessulana." Species: Genista Monspessulana. United States Forestry Service. Web. 14 Oct. 2014. http://www.fs.fed.us/database/feis/plants/shrub/genmon/all.html