1 8-2 RUTACEM. [chap. 



Observe the spur of the posterior sepai of cultivated 

 Pela?'go?nu?H, which is adherent to the pedicel. Its cavity 

 may be easily seen on cutting the pedicel across just below 

 the calyx. In Tropceolum the corresponding spur is free. 

 Note also the beak-like prolongation of the receptacle of 

 the Geranium Tribe after flowering : the closely connivent 

 or coherent anthers of the Balsams : the elastic valves of 

 the fruit-capsules of the latter. 



The Balsams are a pre-eminently Indian group, but the 

 distribution of the species is very circumscribed, many of 

 them being limited to small areas. The beautiful aquatic 

 Hydrocera triflora {Impatie7is natans of the older botanists), 

 differing from Ivipatiens in its distinct petals and berried fruit, 

 is, however, widely dispersed throughout India in ponds and 

 freshwater ditches. The floating and submerged branches 

 of this species are often several yards in length. 



Some species of Oxalis exhibit the phenomenon of " irri- 

 tability " in their leaves. The Blimbing and Carambola are 

 the acid fruits of species of Averrhoa, an arborescent genus 

 allied to Oxalis, native in India. 



25. Natural Order, Rtitacece. — The Rue and Orange 

 Family. 



Usually trees or shrubs with alternate or opposite, com- 

 pound (pinnate tri- or uni-foliolate) leaves, dotted with trans- 

 lucent glands. Stamens as many or twice as many as 

 petals (in Citrus and y^gle indefinite). 



Type — The Orange-tree {Citrus Aiwantiw}!). 



An evergreen, often spinose tree, with alternate, entire, 

 shining, glandular-dotted leaves, and axillary, fragrant, white 

 flowers. 



