In the sandier tracts the ak (Calotropis procera, N.O. Asclepiadaceae), the harmal (Peganum harmala, N.O. Rutaceae), and the colocynth gourd (Citrullus colocynthis, N.O. Cucurbitaceae), which, owing to the size of its roots, manages to nourish in the sands of African and Indian deserts, grow abundantly. Common weeds of cultivation are Fumaria parviflora, a near relation of the English fumitory, Silene conoidea, and two Spergulas
Fig. 19. Banian or Bor trees.
(Caryophyllaceae), and Sisymbrium Irio (Crucif erae). A curious little Orchid, Zeuxine sulcata, is found growing among the grass on canal banks. The American yellow poppy, Argemone Mexicana, a noxious weed, has unfortunately established itself widely in the Panjab plain. Two trees of the order Leguminosae, the shisham or tali (Dalbergia Sissoo) and the sir is (Albizzia lebbek), are commonly planted on Panjab roads. The true home