This section is from the book "The Botanical Magazine; Or, Flower-Garden Displayed", by William Curtis. Also available from Amazon: The Botanical Magazine; or, Flower-Garden Displayed, Volume I.
Convolvulus Purpureus. Purple Bindweed, or Convolvulus Major.
Corolla campanulata, plicata. Stigmata 2. Capsula 2-locularis; loculis dispermis.
CONVOLVULUS purpureus foliis cordatis indivisis, fructibus cernuis, pedicellis incrassatis. Linn. Syst. Vegetab. ed. 14. Murr. p. 200.
CONVOLVULUS purpureus folio subrotundo. Bauh. Pin. 295.
CONVOLVULUS caeruleus major rotundifolius. The greater blew Bindweede or Bell-flower with round leaves. Park. Parad. p. 358.
"Is an annual plant which grows naturally in Asia and America, but has been long cultivated for ornament in the English gardens, and is generally known by the title of Convolvulus major. Of this there are three or four lasting varieties; the most common hath a purple flower, but there is one with a white, another with a red, and one with a whitish-blue flower, which hath white seeds. All these varieties I have cultivated many years, without observing them to change. If the seeds of these sorts are sown in the spring, upon a warm border where the plants are designed to remain, they will require no other culture but to keep them clear from weeds, and place some tall stakes down by them, for their stalks to twine about, otherwise they will spread on the ground and make a bad appearance. These plants, if they are properly supported, will rise ten or twelve feet high in warm Summers: they flower in June, July, and August, and will continue till the frost kills them. Their seeds ripen in Autumn." Miller's Gard. Dict. ed. 4to. 1771.