170 
ELEMENTS OF BOTANY. 
earlier stage (above), but it cannot deposit any pollen on the 
stigmas which are unripe, shut together and tucked aside, out 
of reach. On flying to a flower in the later stage the pollen 
II Ul IV 
Fig. 153.— Provisions for Cross-Fertilization in the High Mallow. 
I, essential organs as found in the bud ; II, same in the staminate stage, the anthers 
discharging pollen, pistils immature; III, intermediate stage, stig, the united 
stigmas ; LV, pistillate stage, the stigmas separated, stamens withered. 
just acquired will be lodged on the prominent stigmas and 
Fig. 154.— Stamens 
and Pistils of 
Round-Leafed 
Mallow (the stig- 
mas curled round 
among the sta- 
mens to admit of 
self-fertilization). 
thus produce the desired cross-fertilization. 
Closely related flowers often differ in their 
plan of fertilization. The high mallow, a 
plant cultivated for its purplish flowers, which 
has run wild to some extent, is admirably 
adapted to secure cross-fertilization with its 
own pollen, since when its stamens are shed- 
ding pollen, as in Fig. 153, II, the pistils are 
incapable of receiving it, while when the pis- 
tils are mature, as at IV, the stamens are 
quite withered. In the common low mallow 
of our door-yards and waysides, insect ferti- 
lization may occur, but if it does not the 
curling stigmas finally come in contact with 
