4 
SALICALES 
Order i. SALICALES 
Salicales Lindley Nat. Syst. ed. 2, 186 (1836) partim ; Engler Fiihrer Bot. Gart. Brest. 31 (1886); Pflanzen- 
fam. Nachtr. 345 (1897). 
For characters, see page 3- Only family : Salicaceae. 
Family 1. SALICACEAE 
Salicaceae Lindley Nat. Syst. ed. 2, 186 (1836); Pax in Engler und Prantl Pflanzenfam. iii, pt. i, 29 
(1894); Ascherson und Graebner Syn. iv, 13 (1908); Salicineae Mirbel Elem. ii, 905 (1815). 
Trees, shrubs or undershrubs. Leaves deciduous. Catkins usually appearing before or at the 
same time as the leaves. Flowers wind-pollinated or insect-pollinated. Filaments usually free. Anthers 
basifixed, extrorse. Ovary subsessile or stalked. Stigmas 2, entire or bifid. 
2 genera ; about 200 species (but see Populus , below), chiefly in the north temperate zone, a 
few subtropical or tropical. 
Genera of Salicaceae 
Genus 1. Populus (see below). Petioles usually long. Laminae usually broad. Staminate 
catkins pendulous at maturity. Stamens more than 5. Bracts more or less laciniate. Perianth 
small, usually entire or subentire. 
Genus 2. Salix (p. 13). Petioles usually short. Laminae usually narrow. Staminate catkins 
usually ascending. Stamens usually 2 — -5. Bracts entire. Perianth modified into 1 or 2, rarely 
more nectaries. 
Genus 1 . Populus 
Populus [Tournefort Inst. 592, t. 365 (1719)] L. Sp. PL 1034 (1753) et Gen. Pl. ed. 5, 456 (1754); Pax 
in Engler und Prantl Pflanzenfam. iii, pt. i, 35 (1894); Ascherson und Graebner Syn. iv, 14 (1908). 
Trees, usually with suckers. Stipules caducous. Petioles often laterally compressed, about as 
long as the laminae. Laminae usually broader than in Salix , lobed or toothed, the lower ones of 
each twig broader and larger than the upper ones. Catkins appearing before the leaves, cylindrical. 
Staminate catkins pendulous at maturity, fugaceous. Pistillate catkins pendulous, spreading, or ascending, 
shorter than the staminate ones, lengthening in fruit. Bracts irregularly crenate or laciniate, usually 
caducous especially on the staminate plants. Flowers dioecious (very rarely diclinous or monoclinous), 
wind-pollinated, protandrous. Perianth small, cup-shaped or saucer-shaped, very rarely lobed, usually 
crenulate or entire, often somewhat zygomorphic. Stamens about 8 to about 60. Ovary often more 
or less adherent to the perianth. Stigmas 2, each usually bifid. Style short. Placentae often large. 
Probably Populus is a more primidve genus than Salix, as shown by the presence of a less specialised perianth, 
by the more numerous and less fixed number of the stamens, by the anemophilous habit which seems to be the primitive 
one in the Amentiflorae, and by the absence of a gynophore. 
Sir J. E. Smith, Eng. FI. iv, 245 — 6 (1828), recognised that our poplars merited more critical examination than had 
been accorded to them ; but no British systematist seems ever to have devoted much attention to them. In the meantime, 
several forms have probably originated by hybridisation; and hybrid-forms and nurserymen’s “sports” are being more and 
more abundantly planted in the country. Whilst little notice is here taken of forms which exist only in cultivation, an attempt 
is made to include those forms which, though planted, have become more or less established in natural or semi-natural 
situations. These forms are met with by botanists in their herborisations ; and they must be understood if our indigenous 
plants are to be correctly distinguished. 
The estimate of the number of species varies greatly. Engler gives 18, Dode about 100, 
Ascherson und Graebner 30. North temperate zone. 
British sections of Populus 
Section I. Leuce (p. 5). Winter-buds small, pubescent, or glabrous, not or scarcely viscous, 
not odorous when opening. Petioles more or less laterally compressed. Laminae hairy or glabrous 
below ; of the sucker-leaves hairy below. Bracts irregularly crenate or laciniate, ciliate often with long 
silky hairs. Perianth obliquely truncate. Stamens (in the British species) about 8 — 12. Pistillate 
catkins rather dense, pendulous. Stigmas 2, greenish-yellow or purplish, more or less slender. Capsules 
more or less narrowly conical. 
