Appearance
When found as a summer annual, the scarlet pimpernel has a low-growing creeping habit, but as a winter annual, it forms a half-rosette with an upright stem. It has weak sprawling stems with square cross-section growing to about 5–30 centimetres long.They bear bright green, soft, ovate sessile leaves in opposite pairs. The orange, red or blue, radially symmetric flowers, about 10–15 millimetres in diameter, are produced singly in the leaf axils from spring to autumn. The petal margins are somewhat crenate and have small glandular hairs. The stamens have lollipop hairs and therefore attract a variety of pollinators, especially flies, but the flowers are also capable of autopollination.
The dehiscent capsule fruits ripen from August to October in the northern hemisphere. The weight of the fruiting body bends the stem, and the seeds are transported by the wind or rain.
Scarlet pimpernel flowers open only when the sun shines, and even close in overcast conditions. This habit leads to names such as "shepherd's weather glass". It has recently started to occur along the verges of salted roads, creating a broad red band along the roadside.
Scarlet pimpernel has a wide variety of flower colours. The petals of the type "arvensis" are bright red to minium-coloured; "carnea" is deep peach, "lilacina" is lilac; "pallida" is white; and "azurea" is blue. The blue form can be difficult to distinguish from "A. foemina", but the petal margins are diagnostic: whereas "foemina" has clearly irregular petal margins with only 5 to 15 glandular hairs, "A. arvensis" f. "azurea" has 50 to 70 hairs on only slightly irregular margins.
References:
Some text fragments are auto parsed from Wikipedia.
