570 
PHANEROGAMS. 
bottom of the flowers, as in Nicotiana and Labiatae. Frequently, however, special 
hollow receptacles are constructed for this purpose, as is especially the case with the 
bag-like appendages of the perianth-leaves (Fig. 396), usually called Spurs. In 
Viola only one of the perianth-leaves forms a hollow spur, into which the ap- 
pendages of two stamens are prolonged and secrete the nectar. The cup-shaped 
stalked petals of Helleborus and the slipper-shaped petals of Nigella secrete at the 
bottom of their cavity the nectar which gathers there. 
The Ovule (macrosporangium) of Angiosperms usually consists of a clearly 
developed, sometimes even very long stalk or Funiculus (as in Opuniia and Plum- 
bagineae) — which, however, is sometimes entirely wanting, as in Grasses — and one 
or two integuments which enclose the nucellus. [The general rule is that the 
ovules of the gamopetalous Dicotyledons have one integument, and that the ovules 
of the apetalous and polypetalous Dicotyledons as also those of the Monocotyledons 
have two integuments. Exceptions occur, however : thus, arftong gamopetalous 
Dicotyledons the Primulaceae, Myrsineae, Plumbaginaceae, and Cucurbitacese have 
two integuments ; and among apetalous and polypetalous Dicotyledons the following 
Fig. 396. — Flowers with spurred sepals {A) and petals [B. C) ; A Riscntella hisfiida, B Epimedium g-randijloi-nm, 
C Aqziilegia canadensis. 
have only one integument, the Loaseae, Pittosporeae, Umbelliferae, Callitriche, 
Empeirum, Hippuris, and Escallonia (Warming).] A third envelope, the Aril, is 
frequently formed subsequently (as in Myristica, Euonymus, Asphodelus lutea, Aloe 
subiuberculaia, &c. When the ovule is the terminal structure of the floral axis, 
and has a short funiculus, it is orthotropous, as in Piperace^e and Polygonaceae ; 
the campylotropous form, i.e. where the nucellus together with its integuments 
is itself curved, is comparatively rare, but occurs in Grasses, Fluviales, Caryo- 
phylleae, &c. The usual form of the ovule of Angiosperms is the anatropous ; 
the nucellus together with its integuments is inverted, so that the micropyle faces 
the point of origin of the funiculus from the placenta (hilum) (Figs. 382, E, 383) ; 
in this case the funiculus runs up the side of the ovule, coalesces with it, and is 
termed the Raphe. The micropyle is frequently, especially in Monocotyledons, 
formed by the inner integument only of the nucellus; but sometimes, especially 
among Dicotyledons, the outer integument grows also above the opening of the 
inner one, and the channel of the micropyle is then formed at its outer part (the 
Exoslome) by the outer, at its inner part (the Endostome) by the inner integument. 
