PROLIFEROUS OR VIVIPAROUS PLANTS. 303 



been found in the interior of Gourds, as well as the fruit of Carica 

 Papaya, the Papaw. 



631. Proliferous Plants. In place of seeds, some plants produce 

 buds which can be detached and produce separate individuals. Flowers 

 which are thus changed into separable buds, are called proliferous 

 (proles, offspring, and fero, I bear), or viviparous (vivus, alive, and 

 pario, I produce). They are met with in many alpine grasses, as 

 Festuca ovina, var. vivipara, Aira casspitosa, var. alpina, Poa alpina, &c., 

 as well as in Alliums, Trifoliums, &c. Buds of a similar kind may be 

 produced on the edges, or in the axil of leaves, as in Byrophyllum 

 calycinum, Malaxis paludosa, many species of Gesnera, Gloxinia, and 

 Achimenes ; and the bulbils of Lilium, Ixia, and Dentaria, seem to be 

 peculiar forms of buds, capable of being detached, and of assuming 

 independent growth. Buds, however, differ from embryos of seeds 

 in the direction of the roots being towards the axis of the plant. 



632. The length of time required for the protrusion of the radicle 

 varies in different plants. Some seeds, as garden cresses, germinate in 

 the course of twenty-four hours, others require many days or many 

 months. Seeds with hard coverings, or a stony perisperm, may lie 

 dormant in the soil for a year or more. The following experiments 

 were made in the Geneva garden, on seeds similarly watered, and ex- 

 posed to a medium temperature of 53 F. It was ascertained that 

 one half of the species of the following families germinated after the 

 lapse of the number of days here mentioned : 



Amaranthacese, 9 days. 



Cruciferse, 10 



Boraginaceze, Caryophyllacese, Chenopodiacece, Malvaceae, ...11 



Compositse, Convolvulaceae, Plantaginacese, 12 



Polygonacea?, , 13 



Campanulacese, Leguminosae, Valerianacese, 14 



Graminese, Labiatse, Solanacea?, 15 



Rosacese, 17 



Ranunculaceae 20 



Antirrhinums, Onagrariaceae 22 



Umbelliferae, 23 



Temperature has a great effect in accelerating germination. Thus, 

 Erigeron caucasicum, at a temperature varying from 49 to 53, ger- 

 minated in ten days; at a temperature from 66 to 72, in two days ; 

 Dolichos abyssinicus, at the former temperature, in ten days, at the 

 latter, in three; Zinnia coccinea, in twenty-two, and five days respec- 

 tively. 



633. Duration of the Life of Plants. Plants, according to the 

 duration of their existence, have been divided into annual, biennial, 

 and perennial The first of these terms imports that the seed germinates, 

 and that the plant produces leaves and flowers, ripens its seed, and 

 perishes within twelve months; the second, that a plant germinates 



