THE ARUM TRIBE. 195 



point {jig. 9- a.), or plumule, which eventually becomes 

 the new stem. 



Such is the structure of the spotted Arum. The 

 other genera differ in the spadix being altogether 

 covered with flowers, or in the absence of abortive 

 ovaries, or in the internal structure of the anther and 

 ovary, or even in that of the style and stigma ; but 

 the spathaceous inflorescence distinctly marks the 

 order in all cases. 



EXPLANATION OF PLATE XLVL 



L The Birthwort Tribe. — 1. Leaf and flower of the Zo/i^r-fai^ed 

 Birthwort (Aristolochia trilobata), natural size ; a the stipules ; b the 

 strap-shaped tall of the calyx ; c the horns at the base of the calyx ; d 

 the ovary ; e the notch on one side of the border of the calyx. — 2, The 

 column of stamens d, seated in the base of the calyx a ; b the horns of 

 the calyx ; c the ovary. — 3. An anther separated from the other five. 

 — 4. A transverse section of the ovary. — 5. A seed of another species of 

 Birthwort, natural size. — 6. The same magnified, with half the skin cut 

 off, to shew the embryo a, lying in horny albumen. — 7. The embryo. 



XL The Arum Tribe. — 1. Spathe oi Spotted Arum (Arum ma- 

 culatum), natural size, with the point of the spadix at a. — 2. A spadix 

 taken out of the spathe ; a the base of the spathe ; b ovaries ; c abortive 

 ovaries ; d stamens ; e abortive ovaries ; f part of the stalk of the naked 

 head of the spadix. — 3. An ovary. — 4. A transverse section of the same. 

 — 5. A stamen. — 6. The spadix covered with ripe fruit ; a the withered 

 remains of the spathe. — 7. A ripe seed. — 8. A longitudinal section of 

 the same, shewing the embryo lying in albumen ; a the slit communi- 

 cating with the plumule. — 9. The monocotyledonous embryo, with a 

 portion of its root-end sliced away, and shewing the conical plumule a. 



o2 



