334 BOTANICAL GAZETTE “[ocToBER 
Floral evolution.—In a series of papers published in New Phytologist 
during 1911 and 1912, WERNHAM has discussed floral evolution, especially 
with reference to the phylogeny of the Sympetalae. The last paper’ presents 
the summary and conclusions, and it is announced that the series has now 
appeared in book form e immense amount of material presented cannot 
be mentioned in a review, but the general conclusion is that the Sympetalae 
are polyphyletic, having been derived from the Archichlamydeae along 7 
istinct lines. The names given by the author to these lines will ann oy 
relationship of the various sympetalous orders to those of the A 
The lines are as follows: (x) Centrospermae-Primulales; (2) ment 
Ericales; (3) Guttiferales-Ebenales; (4) Geraniales (Plantaginales)-Con- 
tortae-Tubiflorae; (5) Calyciflorae-Umbelliflorae-Rubiales-Dipsacales; (6) 
Calyciflorae-Campanulatae; (7) Calyciflorae-Passiflorales-Cucurbitales. There 
is also a very useful discussion of the method: of determining plant affinities 
and of the principles of classification —J. M. C. 
Resistance against attack of dodder.—By growing Cuscuta Gronovit on a 
great variety of hosts, GeRTz* has studied various means of protection possessed 
by plants against the attack of dodder. The main means found are mechanical 
resistance to penetration, high concentration of oxalic acid, and presence of 
latex, certain alkaloids, or ethereal oils. Various alkaloids and ethereal oils, 
in the concentration existing in the hosts tested, vary greatly in their effective- 
ness from indifferent to rather highly toxic. In comparing his results wi 
rather fully reported results of other workers, Gertz concludes that different 
species of dodder vary greatly in their resistance to a given protective sub- 
stance. He notes the presence of the 3 characters of dodder often reported: 
resorption of the basal part of the sprout, ability to act in part as an autotroph 
by chlorophyll development, and impermeability of haustoria to certain toxic 
materials. This subject is in need of thorough microchemical and physiological 
study.—WILLIAM CROCKER. 
Cercospora beticola.—Poot and McKave. 28 have made a detailed study 
of the parasitism of Cercospora beticola on the sugar beet (Beta vulgaris), ex 
special attention to climatic factors and the mode of infection. The lea 
that show maximum stomatal opening, both in aperture and in duration e 
opening, showed the greatest susceptibility to infection. Factors that favor 
*s WerNuaM, H. F., Floral evolution, with particular reference to the sympetalous 
dicotyledons. New Phytol. 11:373-397. 1912. 
%* Gertz, Orro., Uber die Schutzmittel einiger Pflanzen gegen schmarotzende 
Cuscuta. Jabrb, Wha: Bot. §6:123-154. 1915. PFEFFER’s Festschrift. 
27 Poot, V. W., and McKay, M. B., Relation of stomatal movement to infection 
by Cercospora ie liing Jour. Agric. Research 5:1011-1038. pls. 80, 81. figs. 6. 1916. 
, Climatic conditions as related to Cercospora beticola. Jour. Agric. 
Research 6: asta pls. 3, 4. figs. 10. 1916. 
