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.
Lotus Jacobaeus. Black-Flowered Lotus.
Legumen cylindricum strictum. Alae sursum longitudinaliter conniventes. Cal. tubulosus.
LOTUS Jacobaeus leguminibus subternatis, caule herbaceo erecto, foliolis linearibus. Lin. Syst. Veg. 601.
LOTUS angustifolia, flore luteo purpurascente, infulae S. Jacobi. Comm. hort. 2. p. 165. t. 83.
This species of Lotus has been called black-flowered, not that the flowers are absolutely black, for they are of a very rich brown inclined to purple, but because they appear so at a little distance; the light colour of the foliage contributes not a little to this appearance.
"It grows naturally in the Island of St. James; is too tender to live abroad in England, so the plants must be kept in pots, and in the winter placed in a warm airy glass cafe, but in the summer they should be placed abroad in a sheltered situation. It may be easily propagated by cuttings during the summer season, and also by seeds, but the plants which have been two or three times propagated by cuttings, seldom are fruitful." Miller's Gard. Dict.
It continues to flower during the whole of the summer; as it is very apt to die off without any apparent cause, care should be taken to have a succession of plants from seeds, if possible.