Cirsium arvense is a
C3 carbon fixation plant. 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 respect to where it has established itself. Differences can be seen in their R-protein mediated defenses, sensitivities to abiotic stresses, and developmental timing.
Taxonomy Cirsium arvense is placed in the subtribe Carduinae, tribe Cardueae of the family Asteraceae. Unlike other species in the same genus, it is
dioecious, although male plants sometimes produce bisexual flowers. It also differs from other native North American species in having large roots and multiple small flower heads on a branched stem. Cirsium arvense grows in diverse habitats (ranging from moist places to grasslands, mountain slopes, flooded lands, disturbed sites, etc.) at 100–4,300 m. Its native range is Temperate Eurasia, Northwest Africa. It has been introduced into North America, South America, Africa, Europe, Asia, Australia, and other regions.
Underground network 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. The fragrance that
C. arvense emits attracts both pollinators and florivores containing compounds that attract each respectively. Honeybees are shown to have the highest visitation rate, followed by other bee species in the genera
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. One to 5 flower heads occur per branch, with plants in very favourable conditions producing up to 100 heads per shoot. ==Varieties==