ALNUS 
87 
I. ALNUS GLUTINOSA. Alder. Plate 89 
Alnus Gerard Herball 1249 (1597); Ray Syn. ed. 3, 442 (1724); A. vulgaris sub-conis ligulis membranaceis 
rubris donata Dillenius in Ray loc. cit. 
Alnus glutinosa Gaertner De Fruct. ii, 54 (1791); Smith Eng. FI. iv, 132 (1828); Syme Eng. Bot. 
viii, 178 (1868); Rouy FI. France xii, 259 (1910); Ascherson und Graebner Syn. iv, 416 (1911); Betula alnus 
var. glutinosa L. Sp. PI. 983 (1753); Betula almis L. FI. Angl. (1754) non Syst. Nat. ; Smith FI. Brit. 1013 
(1804); Betula glutinosa L. Syst. Veg. ed. 10, 1265 (1759); Almis rotundifolia Miller Abr. Gard. Diet. ed. 6, 
no. 1 (1771). 
Tree, attaining a height of about 25 — 28 m. Petioles about a quarter as long as the laminae. 
Laminae oboval to suborbicular, more or less cuneate at the base, serrate, more or less undulate, 
obtuse, truncate, often emarginate more or less glutinous when young. Staminate catkins long, 
cylindrical, pendulous. Pistillate catkins short, oval to cylindrical, suberect or spreading, lengthening 
in fruit, persisting through the following winter. Achenes winged. 
The botanical name of the alder has, in recent years, been unnecessarily confused. Some authorities have resuscitated 
the name Alnus rotundifolia (Miller Abr. Gard. Diet. ed. 6, no. i (1771)); but this name is invalid on account of the existence 
of an earlier trivial name in Betula glutinosa L. Syst. Veg. ed. 10, 1265 (1759). As the plant is now invariably placed in the 
genus Alnus, Gaertner’s familiar name Alnus glutinosa is correct. 
The synonym Alnus rotufidi/olia is sometimes incorrectly cited as of Miller Gardener’s Diet. ed. 8 (1768); but no such 
name appears in this edition. Sometimes too the same synonym is cited as of Miller Gard. Diet. ed. 7 (1759); but this 
also is an erroneous citation. These errors can only be due to an unfortunate habit which many botanists evidently have of citing 
names without taking the trouble to consult the works in which the names are alleged to appear. 
In Fernald and Robinson’s edition of Gray’s New Manual of Botany 337 (1908), the name Alnus vulgaris Hill is 
used for the plant. This name occurs in Hill’s Herb. Brit. 510 (1756); but this work (like the first seven editions of 
Miller’s Gardeners Dictionary , and like the first five editions of the Abridgment of this great work) does not adopt the 
binominal system of nomenclature : the names in it are therefore not available for citation except among works of the pre- 
Linnaean era. If the names of such works are adopted, much confusion will result. 
(a) A. glutinosa var. macrocarpa Loudon Arboret. iii, 1678 (1838); Grenier et Godron FI. France iii, 
150 (1855); Rouy FI. France xii, 260 (1910); A. glutinosa race vulgaris var. macrocarpa Ascherson und Graebner 
Syn. iv, 419 (1911). 
Laminae larger than in var. typica , about as long as broad (7 — 8 cm.), and with larger and coarser 
serrations. Pistillate catkins at maturity and before the seeds have been shed about 3 cm. long. 
Very rare ; Chippenham Fen, Cambridgeshire. 
France, and perhaps elsewhere. 
(b) A. glutinosa var. typica comb, nov.; A. glutinosa var. vulgaris f. typica [Callier ex] Schneider 111 . 
Handb. Laubh. i, 129 (1904); A. glutinosa race vulgaris var. typica Ascherson und Graebner Syn. iv, 418 (1911). 
leones: — Smith Eng. Bot. t. 1508, as Betula alnus ; Hartig Forst. Culturpfl. t. 23, as A. glutinosa. 
Camb. Brit. FI. ii. Plate 89. (a) Twig with staminate and pistillate catkins, (b) Fertile shoot in autumn. 
(c) Pistillate catkin (enlarged), (d) Persistent, empty cone. Huntingdonshire (E. W. H.). 
Laminae intermediate in size and shape between the other two varieties, about 5 — 6 cm. long 
and 4 — 5 broad. Stamhiate catkins about 6 — 12 cm. long. Pistillate catkins about 07 to ro cm. 
long when in flower, and about 17 — 2'o cm. long and ro — 1*4 broad when in fruit. 
We believe this to be the common southern and lowland form ; Suffolk, Norfolk, Cambridgeshire, Huntingdon- 
shire, Somerset, and doubtless elsewhere. Not yet known for Wales, Scotland, or Ireland. It will doubtless prove 
to be rare or absent in hilly and northern districts. 
Central and southern Europe; Algeria (!). 
(c) A. glutinosa var. microcarpa Rouy FI. France xii, 260 (1910); A. glutinosa var. vulgaris f. micro- 
carpa [Uechtritz in Sched. ex] Callier in fahresber. Schlesw. Gesellsch. Vaterl. Cult, xix, pt. ii, 6 (1891); Callier 
ibid. 74 (1892). 
leones: — Sv. Bot. t. 128, as Betula alnus ; FI. Dan. t. 2301, as A. glutinosa ; Reichenbach Icon, xii, t. 631, 
fig- I2 95> as A. glutinosa. 
Exsiccata : — Billot, 647, as A. glutinosa ; Herb. FI. Ingric. iv, 587, as A. glutinosa. 
Laminae smaller (about 4*5 cm. long and 37 — 4'0 broad), and with smaller and finer serrations. 
Catkins shorter. Pistillate catkins about 4 — 5 mm. long and 3 broad, enlarging in fruit up to 
about 1 ’5 cm. long and ro broad. 
