| Dykes, in The Genus Iris, 1913; refers to the Xiphium SectionThe group of bulbous Irises of which the best known representative is I. xiphium, the Spanish Iris, comprises six species all natives of the Iberian Peninsula or of North-West Africa'. The most northern representative, I. xiphioides, is confined to the Pyrenees and the hills of North-Western Spain and is sharply distinguished from the rest of the group both by the form of the segments of the flower and by its requirements in cultivation. In its native home it grows in damp alpine pastures, where moisture is continually oozing through the soil and it is therefore most luxuriant in those gardens that possess a moist soil, rich in humus. It differs, too, from all the other members of the group by the fact that the tips of the leaves do not pierce the surface of the soil until after the New Year, while all the other species appear above the ground in autumn.The other members of this group all delight in a soil that becomes dry and warm in summer, so that their bulbs are adequately ripened. Indeed, they do not continue to flourish unless this ripening of the bulbs takes place. Unless therefore the soil and the climate naturally provide such a resting period, it becomes essential to lift the bulbs when the leaves turn yellow about the end of July or early in August and store them in sand or other dry material for about a month. Bulbs that have been lifted should not be left exposed to the sun and air longer than is necessary to dry the earth that remains clinging to them, or they will begin to wither and lose their plumpness. This frequent, or even annual, lifting of the bulbs has an additional advantage, for it tends to increase the stock of bulbs by allowing all the bulblets a chance to develop. The bulb illustrated on Plate XLIII shows the way in which four or six bulblets are packed closely one above the other in equal numbers on either side of the main bulb. In the wild state, or when the bulbs remain undisturbed in the same position year after year, these lateral bulblets have to struggle for existence against the more vigorous central bulb and therefore often succumb from want of nourishment.In making up a bed for these Irises, sharp drainage is the one essential but the opposite extreme of giving the bulbs pure sand and no nourishment must also be avoided. Heavy soil should therefore be lightened and rendered porous and barren sand enriched by the liberal addition of humus in the form of well-decayed leaf soil or old manure. The addition of some lime or chalk is beneficial. The stock of these bulbs increases rapidly when the offsets are removed and planted out a few inches apart. They grow to flowering size in one or two years and form, of course, the only means of propagating any particular form or variety. Notes on the method of raising seedlings will be found in the chapter on raising Irises from seed, page 235.Speculation of some interest is involved in the question whether bulbous or rhizomatous Irises first made their appearance in the development of the genus. Whatever the truth may be, there is in some ways a striking resemblance between the flowers of I. xiphium and those of I. spuria. The form and poise of the segments is almost identical and I have even had instances of strong growing examples of I. xiphium, which produced an upright lateral branch, precisely like those of I. spuria. Moreover there occurs on the short funnel-shaped tube of each a curious nectarial exudation, which may be seen on Plates XVII and XLIII. This phenomenon is not confined however to these two species, for it is also found in some American species and invariably attracts the attention of ants, often to the detriment of the flowers'.