226 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
American species of Labiatae. By far the larger number are specially 
adapted for the visits of bees. 
In another paper * * * § Mr. Robertson contributes notes on the mode of 
pollination and the insect visitors of Stellaria media, Malva rotundi- 
folia , Sida spinosa, Abutilon Avicennse, Hibiscus lasiocarpus, H. Trionum , 
Geranium carolinianum, Oxalis violacea, and Melilotus alba. 
Mr. J. M‘Leod f explains the contrivances for pollination in nearly 
400 species, natives of Belgium. 
Mr. T. Meehan | records a number of further observations. In 
Malva rotundifolia tbe flowers are never visited by insects and are 
abundantly fertile. Pollination generally takes place within the un- 
opened bud. The flowers of Brunella ( [Prunella ) vulgaris are visited by 
a small species of humble-bee ; but it apparently takes no part in the 
pollination of the stigma, which seems to take place before opening. In 
Lythrum Salicaria cross-pollination appears sometimes to take place 
without the aid of insects. In Bidens bipinnata and Heliopsis laevis the 
stigmas are apparently self-pollinated, as in most Composite. Scutel- 
laria galericulata also appears to be self-pollinated ; it is difficult for 
insects to reach either the anthers or the stigmas. In Trifolium pratense 
the author has observed humble-bees to enter the mouth of the corolla, 
and not to perforate its tube. 
Cross-Fertilization of Cereals.§ — Mr. W. Carruthers epitomizes the 
results which have been obtained from experiments in crossing the 
various varieties of cereals. Self-fertilization is shown to be the rule in 
wheat, by the simultaneous ripening of the stamens and stigma, and the 
partial discharge of the pollen on the stigma before the flower opens. 
Barley is completely self-pollinated in the bud. Of the seven types of 
cultivated wheat, the author regards five, Triticum Spelta , dicoccum , 
vulgare, turgidum, and durum, as forms of one species of which T. Spelta 
is probably the nearest living representative of the original form ; 
T. monococcum is certainly, and T. polonicum probably, a distinct 
species. All the cultivated forms of barley appear to belong to one 
species ; and the same is probably the case with the oat. 
Pollination of Yucca, j — Mr. W. Trelease describes all the American 
species of Yucca, with their contrivances for pollination. Pronuba 
Yuccasella is the chief agent in the pollination of several species. 
Y. Whipplei, belonging to the subgenus Hesperoyucca, has the pollen 
agglutinated into coherent masses. It is ordinarily pollinated by 
P. maculata ; but, when not visited by this moth, can self-pollinate. 
Red Colour of the Perianth.1T — Prof. A. Hansgirg discusses the 
biological meaning of the blood-red colour of the club-shaped appendage 
to the inflorescence of Arum maculatum, of the flowers of Cynoglossum 
officinale and Sanguisorba officinalis, and of the central flower of the 
* Bot. Gazette, xviii. (1893) pp. 267-74. 
f Bot. Jaarb. (Ghent), 1893, pp. 156-462 (many figs.). See Bot. Centralbl,, lvi. 
(1893) p. 177. 
X Proc. Acad. Nat. Sci. Philadelphia, 1893, pp. 294-6, 297-9, 301-6, 308-9. 
§ Journ. R. Agric. Soc. England, iv., 19 pp. and 7 figs. 
I! Ann. Rep. Missouri Bot. Garden, iv. (1893) pp. 181-226 (19 pis.). See Bot. 
Centralbl., 1893, Beih., p. 498. Cf. this Journal, 1893, p. 209. 
•|[ Bot Centralbl., lvi. (1893) pp. 262-3. 
