Populus deltoides Marsh.

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'Carolin' Carolina Poplar

Stems of the long shoots strongly angled, almost winged. Leaves of strong shoots rather thick, triangularovate, longer than wide, usually cordate at the base. Petioles and lower veins tinged with red. Male. A large, heavily branched tree, retaining its foliage until late in the autumn. It attains a large size in the warmer parts of Europe, but is rare in this country and not entirely hardy. It is common in southern France, where it was once much planted for timber, but is giving way there to hybrids such as ‘Robusta’, which grow faster and are easier to propagate. It is an old clone of var. missouriensis, introduced to Europe early in the 18th century, and usually grown under the name P. angulata Ait. ‘Carolin’ is its modern clonal name.

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'Cordata'

Resembling ‘Carolin’, but hardier, easier to propagate, with less angled branches and yellowish green petioles. It also differs in being female. It was described in 1861 from a tree growing in the nursery of Simon-Louis at Plantières near Metz, under the name P. angulata cordata, and was said to have come from the collection of a Monsieur David. It is a parent of P. × canadensis ‘Robusta’. The French authority Pourtet mentions a poplar called ‘Angulata de Chautagne’ which appears to be similar to ‘Cordata’. This was selected around the middle of the last century in the département of L’Ain by the nurseryman Tallissiéu, and cultivated locally.

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var. missouriensis (Henry) Henry

Branches of strong shoots usually strongly angled, bearing leaves up to 6 in. or even 7 in. long, and often longer than wide. Other differences sometimes given, but perhaps not shown constantly, are that the leaves tend to be acute or subacute rather than acuminate at the apex, more finely toothed, and with three or four glands at the junction between blade and petiole. This variety appears to be commonest in the south-east and in the Mississippi basin. Although distinct enough from the small- and short-leaved form of the north-east once known as P. monilifera, it is not clear how it is supposed to differ from typical P. deltoides, since the species was very scantily described by Marshall. It may even be that this variety really represents typical P. deltoides.Of P. angulata Ait. it has been said that it resembles P. deltoides var. missouriensis in foliage, but differs in the abnormal inflorescence-bracts, which instead of being finely laciniate as in other black poplars, are merely dentate, i.e., the thread-like tips to the teeth are lacking. Henry, followed by later authorities, suggested that this character was the result of a mutation that occurred after the introduction of this poplar to Europe. Since, however, the Aiton specimens in the British Museum are without flowers it is impossible to say whether or not this character was shown by the trees from which P. angulata was described, and in the absence of evidence to the contrary it must be assumed that they resembled the wild trees in their inflorescence-bracts, as they do in foliage. It must be added that an examination of herbarium specimens suggests that the peculiar bracts are not a constant feature of the cultivated trees known as P. angulata. It is not unlikely that one and the same clone might vary in this respect according to season or the climate in which the tree is grown. For the clones usually placed under P. angulata, see ‘Carolin’ and ‘Cordata’.