Cirsium arvense

Flowering creeping thistle
Cirsium arvense is a C3 carbon fixation plant. The C3 plants originated during Mesozoic and Paleozoic eras, and tend to thrive in areas where sunlight intensity is moderate, temperatures are moderate, and ground water is plentiful. C3 plants lose 97% of the water taken up through their roots to transpiration.Creeping thistle is a herbaceous perennial plant growing up to 150 cm, forming extensive clonal colonies from thickened roots that send up numerous erect shoots during the growing season. It is a ruderal species.GIven its adaptive nature, Cirsium arvense is one of the worst invasive weeds worldwide. Through comparison of its genetic expressions, the plant evolves differently with respects to where it has established itself. Differences can be seen in their R-protein mediated defenses, sensitivities to abiotic stresses and developmental timing.[2]

TaxonomyEdit
The canada thistle is part of the Cirsium genus, in the subtribe Carduinae, trube Cardueae and family Astreracae. It differs from other species in the same genus given its dioecious flowers. It it also different from other native North American species given its large roots and multiple small flower heads on a branched stem

Underground networkEdit
Its underground structure consists of four types, 1) long, thick, horizontal roots, 2) long, thick, vertical roots, 3) short, fine shoots, and 4) vertical, underground stems. Though asserted in some literature, creeping thistle does not form rhizomes. Root buds form adventitiously on the thickened roots of creeping thistle, and give rise to new shoots. Shoots can also arise from the lateral buds on the underground portion of regular shoots, particularly if the shoots are cut off through mowing or when stem segments are buried.
Shoots and leavesEdit
Stems are 30–150 cm, slender green, and freely branched, smooth and glabrous (having no trichomes or glaucousness), mostly without spiny wings. Leaves are alternate on the stem with their base sessile and clasping or shortly decurrent. The leaves are very spiny, lobed, and up to 15–20 cm long and 2–3 cm broad (smaller on the upper part of the flower stem).

Flower head fragranceEdit
Every plant species has a unique floral fragrance composition. the fragrance that C. arvense emits attracts both pollinators and florivores containing compounds that attract each respectively. Nonnative honeybees are shown to have the highest visitation rate, following other bee species such as halictus and lasioglossum. Hover flies are also commonly seen pollinating the flower heads of this plant. Florivores such as Beetles and Grasshoppers are commonly seen as well. The compounds found in the fragrance may not be in the highest abundance but they are highly attractive. P-anisaldehyde is found in less than 1%, yet it attracts pollinators such as honey bees. This is thought to be the result of additive and synergistic effects from the blend increasing the attraction to the plant. After pollination, it can be seen that fragrance emission decreases in C.arvense. This is regulated through a regulatory feedback mechanism depending on the pollination status of the plant. This mechanism has only been observed in pistillate plants for dioecious C. arvense. Fragrance emission increases with age.The fragrance contains several compounds that attract diverse insects. Looking at certain butterflies species, it can be seen that the fragrance blend is highly attractive to them, being sensitive to their antennae. High antennal response are seen in consequence to the phenylacetaldehyde as well as the terpenes (oxoisophoroneoxide, oxoisophorone, and dihydrooxoisophorone) found in the blend. This was seen in both natural plants emitting the fragrance and emitting the scent synthetically. It is believed that general arousal can be stimulated through exposure of a single compound, whereas the accumulated exposure of all the compounds influence the foraging behaviour of the butterflies.
Flowers and seedsEdit
The inflorescence compound cyme is 10–22 mm (0.39–0.87 in) in diameter, pink-purple, with all the florets of similar form (no division into disc and ray florets). The flowers are usually dioecious, but not invariably so, with some plants bearing hermaphrodite flowers. The seeds are 4–5 mm long, with a feathery pappus which assists in wind dispersal. One to 5 flower heads occur per branch, with plants in very favourable conditions producing up to 100 heads per shoot. Each head contains an average of 100 florets. Average seed production per plant has been estimated at 1530. More seeds are produced when male and female plants are closer together, as flowers are primarily insect-pollinated. The plant can bloom from seed in a year then subsequently the seeds produced can emerge in the following year.[3]


 

Pappus of Cirsium arvense




 

A creeping thistle with a "cuckoo spit"

3-6 hours of sun per day, with protection from intense mid-day sun

Cirsium Arvense

Cirsium arvense

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