178 REPORT OF THE CONFERENCE ON GENETICS. 
PHENOMENA OF HYBRIDISATION IN THE GENUS 
MENTHA. 
RESUME OF THE FACTS ACQUIRED 
By M. Ernest Mauinvavp. 
I.—THE CARDINAL SPECIES IN THE GENUS MentuHa. 
We call “ cardinal’ * the five irreducible Linnean species, which con- 
stitute the group of Humenthe: M. rotundifolia, sylvestris, viridis, 
aquatica, and arvensis. 
IIl.—TuHeE Signs oF HYBRIDISATION IN THE GENUS Wenraa. 
The Huwmenthe present numerous phenomena of hybridisation, of 
which several exhibit remarkable persistence. 
M. rotundifolia and sylvestris are hybridised regularly, wherever they 
are to be found esrowing together, or in the vicinity of each other, 
except for very rare exceptions due to local circumstances. The indi- 
viduals resulting from these crossings frequently appear in such 
abundance that we might be led to suppose that they are the legitimate 
dominant species, and some authors, Fries, Godron, &c., through a most 
unfortunate error, have referred the M. sylvestris type to M. viridis,t as 
var. canescens. 
Mentha aquatica and arvensis cross with the same facility as the 
preceding, and produce the innumerable varieties of M. sativa L.$ 
M. viridis, rave in France in the wild state, but often cultivated or 
escaped from gardens, takes part in various hybridisations when it 
meets either with M. rotundifolia (M. Lamyi Mlvd.), Nowletiana 
Timb., rubra Sm., gentilis L. &e.,|| or with M. arvensis or with a 
variety of garden origin, and in this case the results are more or less 
complex. 
The M. aquatica crosses in our country rarely with M. rotundifolia 
(iM. Maximiliana F. Schultz, M. Schultzii Bout.), and still more 
rarely with M. sylvestris (M. pubescens Willd., nepetoides Lej., Ayasser 
Mlvd.).4] 
The products from the group arvensi-rotundifolia, without being 
frequent, are less rare than the preceding (M. Muelleriana and Wohl- 
* See Bull. Soc. bot. Fr., xxiv. (1877); Rev. bibl., p. 43. 
¢ Malinvaud, Menthe exsiccate, presertim gallice, Nos. 8, 10, 111, 113, 114, 
115, &c. 
t Grenier & Gordon, Flora of France, ii. p. 650. 
§ Malinvaud, Menthe exs., Nos. 42-50, 53-55, 57, 59, 60, &e. 
|| The same, Nos. 13 (M. sapida), 15 (Nowletiana), 21 (piperita), 38 (citrata), 
61 (rubra), 63 and 65 (gentilis), 178 (cantalica), &e. 
“| The same, Nos. 22 (pubescens), 23 (nepetoides), 24 and 25 (pubescens), 
26 (rotundifolio-hirsuta), 27 and 28 (Maximiliana), 29 and 30 (Schultzii). 
