This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
This plant has not been discovered in any of the early deposits. It is found to-day in the Warm Temperate Zone in Europe, N. Africa, and Western Asia, and is introduced in the United States. It is found in all the counties of Great Britain except Kirkcudbright, Stirling, Mid Perth, Westerness, Main Argyle, Dumbarton, Clyde Isles, S., Mid, and N. Ebudes, W. Ross, Sutherland, Caithness, and the Northern Isles. There is some doubt as to whether in Moray and west of the Caledonian Canal it is indigenous. It is thus much rarer in Scotland. In Ireland it is common.
Dyer's Weed or Weld may be regarded as a native, but as a dye-yielding plant its extension of range may be due in part to this cause. It is fond of high ground, hilly places, where the soil is dry and it can live as a xerophile. It is a lime-loving plant, preferring a limy soil. It is also found on waste ground, to which it travels with other aliens like Lepidium Draba, L. campestre, and others of similar status.
It is a tall, erect, graceful plant, its nodding spike being heliotropic or turned to the sun, as Linnaeus noted. The leaves are entire, long, and shining, elongate-lance-shaped, and the stem is unbranched. The flowers are yellowish-green, in long terminal pointed spikes, with 4 sepals, the petals longer, and many stamens (20-24), which are very marked. The fruit, a capsule, is flattened, broad, and trilobed, with nearly round, smooth, shining black seeds.
The plant is often 3 ft. high. It flowers in July and August, and is biennial, being propagated by seeds.
In the allied Reseda odorata the receptacle becomes raised into a perpendicular square plate between the stamens and sepals, at first yellow, and brown after flowering is over. Honey is secreted by it, and it acts as a honey-guide. The expanded claws or stalks of the 3 upper and middle petals lie close below the lower surface of this plate, and surround the upper lateral margins with lobes pointed anteriorly, serving to protect the honey from the rain as in a box. The laminae of the petals are split up into strips, and render the flowers conspicuous.
The flower does not require to expand, the parts of the flower lying open. The honey-glands secrete honey. The anthers bend down, open, and rise up towards the honey-disk. Three or four carpels develop papillae. The stigma projects considerably above the middle of the flower, forming a resting-place for insects, and is covered with pollen from other flowers. If insects do not visit it self-pollination ensues. The visitors are Hymenoptera (Apidae), Prosopis communis, Apis mellifica, Andrena. Prosopis, a bee with a trowel-like proboscis, is enabled to lift the box formed by the petals over the honey-disk, and in so doing touches the stigma, and becomes dusted also with pollen.
Dyer's Weed (Reseda Luteola)
The seeds are dispersed by the wind. The capsules opening above the seeds are blown out beyond the area of the parent plant, aided by the wind.
Dyer's Weed is a sand plant, requiring a sand soil, and at the same time is a lime-loving plant, subsisting on a lime soil, being found in chalky or oolitic districts.
No fungi are parasitic on this plant. The Thysanoptera Me/ano-thrips obesa, Aiolothrips parasitica, and the Lepidoptera, Bath White (Pieris Daplidice) and Scarce-bordered Straw (Heliothis armiger) feed on it, as also Bright-line Brown-eye (Mamestra oleracea).
Pliny gave the name Reseda, from resedo, I calm, because it was supposed to be a sedative. Luteola is a diminutive of lutea, yellow.
The English names are Ash of Jerusalem, Dyer's Rocket, Dyer's Weed, Dyer's Yellow-weed, Goud, Green-weed, Italian Rocket, Weld, Woad, Wolds or Woulds, Woold, Yellow Rocket, Yellows. It is called Base Rocket because its leaves are like a rocket, and from being used as a base in dyeing wool. It was used as a yellow and green dye to colour wool and cotton. Dutch pink is also manufactured from it. The dye has also been applied to silk, and for paper, mohair, and linen. Blue cloth is dipped in it to dye it a green colour. When the plant is in flower it is plucked up, and used in the fresh and the dried state.
When wild it is biennial, the root and radical leaves being developed the first year. The cultivated plant grown from seeds in the spring is annual.
Essential Specific Characters:40. Reseda Luteola, L. - Stem tall, erect, leaves shining, undivided, lanceolate, flowers yellow, in a terminal spike, petals unequal, exceeding the 4 sepals, capsule flattened.