ARACEAE 



49 



present in the 1. of Monstera. See Monstera, Rhaphidophora, Philo- 

 dendron, Helicodiceros, Dracontium, Zamioculcas, &c. 



Roots adv. and mostly formed above ground in the larger forms. 

 Two types of aerial r. climbing and absorbent. The former, like 

 ivy, insensitive to gravity, show great negative heliotropism ; they 

 cling closely to the support and force their way into the crevices. 

 The latter, insensitive to light, respond markedly to gravity ; they 

 grow down to the soil and enter it, branching out and taking up 

 nourishment. 



The larger trop. A. show interesting stages in the development 

 of epiphytism. The climbing forms grow to considerable size and 

 form longer and longer aerial r. as they grow upwards. The original 

 r. at the t.ase thus become of less and less importance and they often 

 die away together with the lower end of the stem, so that the plant 

 thus becomes an epiph. Of course, as it still obtains its water &c. 

 from the soil, it is not an epiph. in the sense that e.g. many Orchids 

 or Bromeliaceae are such, and it is evident that if this method of 

 becoming epiph. were the only one found in the order, these plants 

 could with no more justice be classed as true epiph. than the ivy 

 which may often be seen in the ' bowls ' of pollard willows in Europe, 

 and which has come there by climbing up the trunk and dying away 

 below. It is found however that some sp. of Fhilodendron, Pathos, 

 &c. are able to commence life as epiphytes. The fleshy fr. is eaten 

 by birds and the seed dropped on a lofty branch. The seedling 

 forms clasping r. and dangling aerial r. which grow steadily down to 

 the soil, even if it be 100 feet or more away. It is hardly possible to 

 suppose that these true epiph. sp. have been evolved in any other way 

 than from former climbing sp. Lastly, some sp. of Anthurium &c. are 

 true epiph. without connection with the soil (e.g. A. Hiigelii Schott 

 = A. Hookcri Kunth.) ; they have clasping r. and also absorbent r. 

 which ramify amongst the humus collected by the pi. itself. The 

 aerial r. of some A. possess a velamen like Orchids. The 1. of 

 Philodenaron cannifolium Schott have swollen petioles full of large 

 intercellular spaces lined with mucilage. When rain falls these fill 

 with water and act as reservoirs. [Cf. Schimper's Epiph. Veg. 

 A merikas. ] 



Fls. without br., usu. massed together on a cylindrical spadix 

 enclosed in a large spathe ; the spadix usu. terminates a joint of the 

 sympodium (the 'continuation' bud is generally in the axil of the 1. 

 next but one before the spathe), so that there is only one formed each 

 year. Fl. $ or monoec. (dioec. in Arisaema), with or without P. 

 Sta. typically 6 but usually fewer (down to i), often united into 

 a synandrium (e.g. Colocasia, Spathicarpa) ; in Ariopsis the synandria 

 again united to one another. Stds. often present, and these also may 

 be fused into a synandrodium as in Colocasia. G with much variety 

 of structure ; frequently reduced to i cpl. Berry. Outer integument 

 of seed often fleshy. Endosperm or none. 



Fls. usu. protog. (even when monoec.). In many gen. (incl. most 

 Eur.) the smell is disagreeable an 1 attracts carrion flies as pollen 

 carriers (see. Arum, Dracunculus, Helicodiceros, &c. ). 



Many A. contain .latex, which is usually poisonous but is dispelled 



W. A 



