The Narrowleaf Hawksbeard, Crepis tectorum, is a annual or winter annual plant ranging from 30-100cm in height. It is an invasive species and during maturity it has one main stem, which is branched, hairless, and leafy. The leaves are arranged in an alternate manner and are less than 0.5 inches wide. The Greek word “krepis” means sandal or slipper which resembles the shape of the seed. Narrowleaf Hawksbeard orginated in Siberia and was introduced to Canada around 1890.

Distribution

Crepis tectorum occurs all throughout Canada, northern parts of the continental United States, and Alaska. It was first discovered in 1974 in Fairbanks, Alaska. Narrowleaf Hawksbeard is now commonly found in the parkland zone of Alberta, Saskatchewan and Manitoba. Crepis tectorum is found in waste areas, conventional tillage, reduced tillage, forage and hay fields, and roadsides.

Identification

Crepis tectorum is identified by its long, erect stem and yellow, dandelion-like flowers. The leaves are pointed and lobed with a length of 10-15cm and width up to 4cm. The flower heads look like they contain single flowers, but in fact they contain many ray florets. http://en.wikipedia.org/wiki/Floret#floret

Seedling

Crepis tectorum may look similar to a dandelion at this stage but will have teeth that point downward on the underside leaf margin. The cotyledon

Cotyledon

A cotyledon , is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants...

s are oval and the first true leaves are more elongated with petiole

Petiole

Petiole may refer to:*Petiole , the stalk of a leaf, attaching the blade to the stem*Petiole , the stem formed by a restricted abdominal segment that connects the thorax with the gaster in the suborder Apocrita...

s.

Juvenile

The juvenile stage of the Narrowleaf Hawksbeard is distinguishable by its rosette (botany)

Rosette (botany)

In botany, a rosette is a circular arrangement of leaves, with all the leaves at a single height.Though rosettes usually sit near the soil, their structure is an example of a modified stem.-Function:...

. The stem may contain a milky-white substance.

Mature

A mature Crepis tectorum plant will have dandelion-like flowers, with many flowers on each stem. When the plant had gone to seed it will have a white, fluffy head where the flower used to be. The stem will contain a milky-white substance. The seeds are dark purple/brown achenes dispersed by the wind using hairs called Pappus (flower structure)

Pappus (flower structure)

The pappus is the modified calyx, the part of an individual disk, ray or ligule floret surrounding the base of the corolla, in flower heads of the plant family Asteraceae. The pappus may be composed of bristles , awns, scales, or may be absent. In some species, the pappus is too small to see...

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Habitat and ecology

Crepis tectorum is an annual weed that grows in cultivated fields and roadsides. It is very invasive so it can take over a field and lead to serious ecological impacts for the surrounding. Crepis tectorum is able to grow in calcareous

Calcareous

Calcareous is an adjective meaning mostly or partly composed of calcium carbonate, in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.-In zoology:...

 soil as well as soil that does not contain lime. However, it grows best in nutrient rich soils containing clays and loams. It also thrives in dry, coarse soil. It grows with other species in the wild however, it becomes infectious if not controlled by humans. It can easily be removed by hand, although it can be controlled better by chemical means. The presence of the Narrowleaf hawksbeard is damaging to the soil and other species of plants nearby as it generally takes over the area. The temperature range for germination is between 2-4 degrees Celsius with optimum depth of 3-4 cm.
narrow-leaved hawk'sbeard
grows on both calcareous and limedeficient
soils

Morphology

Individuals of this species are usually approximately 3 feet tall, single stemmed, yellow colored petals on flowers, and produce 30-70 yellow ray florets.

Flowers and fruit

Flowers of Crepis tectorum are approximately ½- ¾ inches wide and are hermaphrodite, having both male and female organs. It produces small flowers from June until September. The fruit is cylindrical shaped and dark brown. Crepis tectorum's fruit is dry and is called an achene

Achene

An achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent...

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Methods of Control

Narrowleaf Hawksbeard responds best to a fall application of 2,4-DB

2,4-DB

2,4-DB or 4-butyric acid is a selective systemic phenoxy herbicide used to control many annual and perennial broadleaf weeds in alfalfa, peanuts, soybeans, and other crops. Its active metabolite, 2,4-D, inhibits growth at the tips of stems and roots. It is classified in toxicity class III...

 herbicide. Non-chemical methods of control include spring or fall tillage

Tillage

Tillage is the agricultural preparation of the soil by mechanical agitation of various types, such as digging, stirring, and overturning. Examples of human-powered tilling methods using hand tools include shovelling, picking, mattock work, hoeing, and raking...

to control winter annuals and the correct use of agronomic practices such as fertilization for the control of annuals. Biological control can be achieved by insects, non-domestic animals, microorganisms, and viruses. However, the use of biological control can be risky and should always be approached with caution.