In Tribe 5 of Bentham and Hooker, the sleep-movements of species in 12 genera have been observed by ourselves and [page 354] others, but only in Robinia with any care.  Psoralea acaulis raises its three leaflets at night; whilst Amorpha fruticosa,* Dalea alopecuroides, and Indigofera tinctoria depress them.  Ducharte** states that Tephrosia caribaea is the sole example of “folioles couchées le long du pétiole et vers la base;” but a

Fig. 145.  Lotus Creticus:  A, stem with leaves awake during the day; B, with leaves asleep at night.  SS, stipule-like leaflets.

similar movement occurs, as we have already seen, and shall again see in other cases.  Wistaria Sinensis, according to Royer,*** “abaisse les folioles qui par une disposition bizarre sont inclinées dans la même feuille, les supérieures vers le

* Ducharte, ‘Eléments de Botanique’, 1867, p. 349.

** Ibid., p. 347.

*** ‘Ann. des Sciences Nats.  Bot.’ (5th series), ix. 1868. [page 355]

sommet, les inférieures vers la base du petiole commun;” but the leaflets on a young plant observed by us in the greenhouse merely sank vertically downwards at night.  The leaflets are raised in Sphaerophysa salsola, Colutea arborea, and Astragalus uliginosus, but are depressed, according to Linnaeus, in Glycyrrhiza.  The leaflets of Robinia pseudo-acacia likewise sink vertically down at night, but the petioles rise a little, viz., in one case 3o, and in another 4o.  The circumnutating movements of a terminal leaflet on a rather old leaf were traced during two days, and were simple.  The leaflet fell slowly, in a slightly zigzag line, from 8 A.M. to 5 P.M., and then more rapidly; by 7 A.M. on the following morning it had risen to its diurnal position.  There was only one peculiarity in the movement, namely, that on both days there was a distinct though small oscillation up and down between 8.30 and 10 A.M., and this would probably have been more strongly pronounced if the leaf had been younger.

Coronilla rosea (Tribe 6).—­the leaves bear 9 or 10 pairs of opposite leaflets, which during the day stand horizontally, with

Fig. 146.  Coronilla rosea:  leaf asleep.

their midribs at right angles to the petiole.  At night they rise up so that the opposite leaflets come nearly into contact, and those on the younger leaves into close contact.  At the same time they bend back towards the base of the petiole, until their midribs form with it angles of from 40o to 50o in a vertical plane, as here figured (Fig. 146).  The leaflets, however, sometimes bend so much back that their midribs become parallel to and lie on the petiole.  They thus occupy a reversed position to what they do in several Leguminosae, for instance, in Mimosa [page 356] pudica; but, from standing further apart, they do not overlap one another nearly so much as in this latter plant.  The main petiole is curved slightly downwards during the day, but straightens itself at night.  In three cases it rose from 3o above the horizon at noon, to 9o at 10 P.M.; from 11o to 33o; and from 5o to 33o—­the amount of angular movement in this latter case amounting to 28o.  In several other species of Coronilla the leaflets showed only feeble movements of a similar kind.