482 
MILTONIA 
Miltonia Lindl. Orchidaceae (28). 17 sp. trop. Am. Epiphytes. 
Mimosa Linn. Leguminosae (1. 3). 350 sp. trop. and sub-trop. Am., 
a few in Afr. and As. M. pudica L., the sensitive plant, is now a 
common weed in many trop. lands and is universally cultivated in 
hot houses. The genus consists mainly of herbs and undershrubs, 
frequently with stipular thorns. M. pudica has a bipinnate leaf with 
four secondary petioles. It is exceedingly sensitive, and a touch or 
shake will make it move rapidly into the position which it assumes at 
night. The leaflets move upwards in pairs, closing against one 
another, the secondary petioles close up against ome another and the 
main petiole drops through about 6o°. After a short time the move- 
ments are slowly reversed. They are effected by the aid of a pulvinus 
or swollen joint at each point of movement. Each pulvinus can be 
made to work independently of the rest by gentle stimulation, and 
the propagation of the stimulus from pulvinus to pulvinus may also be 
seen. [For physiology of the process see text-books.] The ribs of 
the fruit are frequently thorny and are usually dropped on dehiscence. 
Mimulus Linn. Scrophulariaceae (11. 8). 80 sp. extra- trop. Am., S. 
and E. As., Austr., E. Afr. Several are favourite garden plants and 
one of these, M. luteus L., the yellow monkey-flower, has become 
naturalised in Brit, on river-banks &c. M. moschatus Dougl. is the 
common musk-plant of cottage windows. Insects entering the flr. 
touch first the stigma, which is sensitive to contact and closes up, so 
that self-pollination by the retreating insect is prevented (cf. Martynia). 
Mimusops Linn. Sapotaceae (11). 65 sp. trop. M. Balata Crueg. 
(M. globosa Gaertn.; Guiana) yields a gutta-percha (Balata). M.elata 
Allem. is the Brazilian milk tree or Masseranduba. The timber is 
hard and durable, the fruit edible, “ but strangest of all is the vege- 
table milk, which exudes in abundance when the bark is cut ; it has 
about the consistence of thick cream... also used for glue... as it 
hardens by exposure to air it becomes a tough substance resembling 
gutta-percha ” (Wallace, A?nazon , ch. II.). 
Mina Cerv. = Ipomoea Linn. [M. lobata Cer v. = /. versicolor .] 
Mirabilis Riv. ex Linn. (excl. Oxybaphus L’Herit.). Nyctaginaceae (1). 
10 sp. trop. Am. At the base of the flr. is an involucre of 5 leaves 
resembling a calyx; it is really the bracts of a 3-flowered dichasial 
cyme, of which in most sp. only the central flr. is developed. In some 
sp., however, e.g . M , . coccinea Benth. et Hook, f., the involucre encloses 
more than 1 flr. The flr. opens in the evening and is protogynous 
(in M . Jalapa L. and other common garden sp.), with ultimate auto- 
gamy on withering. The involucre often forms a parachute on the 
fruit. The tuberous roots of M. Jalapa L. (false jalap, four-o’clock, 
marvel of Peru) were formerly used as jalap. 
Mirbelia Sm. Leguminosae (ill. 2). 16 sp. Austr. 
Mitchella Linn. Rubiaceae (11. 17). 2 sp. N. Am. (M. repens L.) and 
Japan. Dimorphic heterostyled. The firs, are in pairs with united 
