428 ANGIOSPERMAEMONOCOTYLEDONES 



2678. I. xiphioides Ehrh.{\. pyrenaica Bub.). (MacLeod, ' Pyreneenbl..' 

 pp. 3069.) The large flowers of this species belong to class Hb. They are blue 

 in colour, with yellow stripes on the sepals as nectar-guides. Their mechanism 

 agrees with that of the preceding species, but a proboscis only 7 mm. long can suck 

 all the nectar. No oecological forms, however, can be properly distinguished as in 

 I. Pseudacorus, as numerous transition-forms occur between flowers with a larger 

 or smaller distance between stylar branches and the sepals. 



Visitors. MacLeod (Pyrenees) observed the humble-bee Bombus hortorum L. 5. 

 which backed out of the flowers when leaving them. Loew (Berlin Botanic Garden) 

 saw the honey-bee, vainly skg. 



2679. I. pumila L. (Warnstorf,Verh.bot.Ver., Berlin, xxxviii, i896,pp.55-6.) 

 In flowers of this species the anthers are sometimes situated below the stigmatic 

 lappets, and sometimes project beyond them. In the former case the visitors on 

 creeping in must first touch the papillose inner surface of such a lappet, while in the 

 other flowers they only come into contact with the outwardly dehiscing anther and 

 dust their upper-side with pollen. Anthesis lasts only one day. The large pollen- 

 grains are very irregular, white in colour, with prominent tubercles often united into 

 ridges, up to loo /i, in diameter. 



2680. I. graminea L. (Knuth, Bot. Centralbl., Cassel, Ixxv, 1898.) In this 

 species the distance between the stigmatic lappets and the large sepals marked with 

 nectar-guides is so small that the honey-bee can only force its way through with 

 difiiculty to get to the nectar. It brushes the stigmatic lappet in doing so, and 

 dusts the downwardly bent upper-side of this with foreign pollen, gathering a fresh 

 supply on going further into the flower by brushing against the dehisced anther. The 

 nectar-tube is 5-5^ mm. long, and therefore corresponds exactly to the length of the 

 honey-bee's proboscis, which is about 5-6 mm. 



I saw the beautiful, violet-blue flowers, which possess an odour of nectar 

 (resembling that of plums, according to the Plant Catalogue), on June 18, 1898, 

 in the garden of the Oberrealschule in Kiel visited by numerous individuals of Apis 

 mellifica L. 5, which eff"ect pollination as has been described above. They usually 

 crept out of the flower sideways after sucking nectar, but in many cases, where the 

 lateral entrance was narrow, also backwards out of the entrance; this, however 

 apparently caused them considerable trouble. 



2681. I. sibirica L. (Loew, ' Bliitenbiol. Floristik/ pp. 346-7 ; Dodel-Pot 

 ' Iris sibirica.') The fragrant blue flowers of this species possess arcuate sepal 

 46-51 mm. long, with a beautiful marking as nectar-guide. They are blue, wit 

 darker forked veins, and yellow at their greatly contracted base, with violet croa 

 veins, some longitudinal veins of a medium blue, and blue streaks on a white ground| 

 further up there is a larger white patch with blue veinings. There is a white bord 

 about 3 mm. high, with bluish markings, on both sides of the base of the sepals ; 

 rests on each side against a small, tooth-like projection of the narrowed base of 

 petals. These are erect, and blue in colour, delicately veined. The three petaloij 

 stylar branches are situated fairly close to the sepals and project 6-9 mm. beyond 

 stamens below them. 



Loew and Dodel-Port describe the flowers as protandrous. The anthers 



