106 



DICOTYLEDONS 



And as every architect is careful to make his work as strong 

 as possible with the least amount of material, so we see here also 

 that the middle part which, as we have seen, has not to contribute 

 anything towards the strength of the stem, remains liolloiv or 

 filled with soft pith only. 



Moreover, as a matter of fact, it is easier to break a long 

 tube than a short one We, therefore, find the stem of the plant 

 divided into many short pieces by nodes at the parts from where 

 the leaves issue. These nodes are solid. The pieces between 

 the nodes are termed intern odes. 



3. The Flowers are arranged in opposite cymose fascicles 

 on the nodes of the upper part of the stems. Calyx funnel- 

 shaped, oblique-mouthed, with ten 

 short teeth and as many nerves. 

 Corolla bilabiate. The lower lip is 

 broad, three-lobed, and forming the 

 conspicuous part of the tlower, at- 

 tracting by its milk-white colour 

 insects, wdiicli know quite well that 

 flowers usually contain sweet honey. 

 If you pull out one of the flowers and 

 suck it, you will And that there real- 

 ly is a tiny drop of honey in each. 

 The upper lip is much smaller and 

 shelters, under its hairy hood or helmet, four stamens of which the 

 two exterior ones are a little longer than the two interior ones. 



If you now put a 

 pencil into the throat of 

 the flower, the stamens 

 will slightly protrude 

 from tlieir sheltered 

 place and rub them- 

 selves against the pen- 

 cil. The same thing 

 happens when a bee or 



other insect tlirusts its proboscis into tlie llower-tube to fetch 

 tlie honey. The stamens l)end forward and deposit tlieir jioUcn- 



Fig. 101. — Vertical section of the 



Hower of Tumbe {Leucas nspera), 



only two stamens are visible. 



Vv^. 102. — LipHower of Salvia, and beo. 



