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Salicaceae
Salicaceae Distribution Willow family Traditionally the family only contained the willows (Salix) and poplars (Populus). However, recent classifications have expanded the number of genera to 55 with over 1,000 species. Distributed worldwide in temperate and tropical areas. Important members Salix – Willows Populus – Poplar, Aspen Idesia Poliothyrsis Salicaceae Characteristics Temperate and tropical trees and shrubs. Salicaceae Characteristics Leaves are simple and usually alternate. Leaves often display salicoid teeth – veins terminate in a gland on the leaf margin. Salicaceae Characteristics Flowers are variable and can be bisexual or unisexual. Petals may or may not be present. Inflorescences are also variable and are catkins in the Salicoideae subfamily. Salix Samyda Salicaceae Characteristics Fruits can be capsules, berries or drupes. Seeds often produce an aril or a tuft of hairs. Dovyalis Salix Salicaceae Economic uses Landscape ornamentals Medicinal – Aspirin-like Timber for pulp Salicaceae Economic uses Wood for Osier baskets Salicaceae Populus deltoides – Eastern cottonwood Eastern cottonwood is a common tree along water courses around the upper Midwest. It is a large tree usually reserved for ornamental use only in difficult growing areas. Native from central Canada to Texas. Salicaceae Populus deltoides – Eastern cottonwood Growth habit – A large tree that is pyramidal when young and with an open irregular crown with age. Tree size – Fast-growing and weak wooded. Trees can reach 100 feet tall. Salicaceae Populus deltoides – Eastern cottonwood Flower – Flowers are in pendulous catkins with male and female flowers on separate plants. Each male flower can have up to 60 stamens with red anthers. Female flowers Male flowers Salicaceae Populus deltoides – Eastern cottonwood Fruit – Fruits are small capsules that release seeds with tufts of cottony hair for flight. Seeds drop and spread in mass in the late spring and can be a nuisance. Salicaceae Populus deltoides – Eastern cottonwood Leaf – An entire deltoid-shaped leaf with a dentate margin. Petioles are flattened and the leaf flutters in the wind. Yellow autumn color. Salicaceae Populus deltoides – Eastern cottonwood Culture: Full sun. Trees prefer deep, moist soil, but is very adaptable and tolerates difficult urban sites. Eastern cottonwood is considered a “messy” tree and will drop plant parts almost any time of the year including the cottony seeds, broken limbs and leaves. Hardy in zones 9 to 3. Salicaceae Populus deltoides – Eastern cottonwood Cultivars: ‘Siouxland’ – A fast growing male selection that does not produce nuisance seeds. Salicaceae Populus deltoides – Eastern cottonwood Cultivars: ‘Sparks’ – A columnar selection that is also a male. Plants can reach over 40 feet tall with halve the spread. Salicaceae Populus hybrids – Hybrid poplars Most hybrid poplars have P. deltoides in their parentage. The first hybrids were derived from P. deltoides and P. nigra called Carolina poplars (P. xeuramericana). Newer hybrids usually include P. trichocarpa, as well as other species. Salicaceae Populus hybrids – Hybrid poplars Hybrids grow very fast (5 feet per year or more) and are used for a variety of uses, especially short rotation crops for pulp and biomass energy. Salicaceae Populus hybrids – Hybrid poplars In the landscape, they can be a short-lived solution where quick tree size is needed. Salicaceae Populus hybrids – Hybrid poplars Poplars will make fast growing large screens. They can be used as nurse trees where more desirer able slower growing plants will replace them in time. Salicaceae Populus nigra ‘Italica’ – Lombardy black poplar Black poplar is not usually seen in cultivation except as ‘Italica’ Lombardy black poplar is a popular fast growing columnar tree. It is still widely used, but it is usually short-lived because of disease susceptibility. Black poplar is native to Western Europe and Lombardy black poplar is an old cultivar selected in Lombardy, Italy in the 1600’s. Salicaceae Populus nigra ‘Italica’ – Lombardy black poplar Growth habit – Lombardy black poplar is an upright, columnar tree. Tree size – Fast-growing trees can reach 70 feet tall and 15 feet wide. Salicaceae Populus nigra ‘Italica’ – Lombardy black poplar Leaf – An entire rhombic to triangular-shaped leaf with a serrate margin. Petioles are flattened. Brief yellow autumn color. Salicaceae Populus nigra ‘Italica’ – Lombardy black poplar Culture: Full sun. Trees are adaptable and tolerate difficult urban and rural sites. Poplar canker infects the upper branches and trunk leading to premature death of trees. Hardy in zones 9 to 3. This planting of Lombardy poplars originally had 10 trees, but only three are surviving. The rest have succumbed to stem canker. Salicaceae Salix sp. – Willow Salix is a large genus with between 200 and 400 species native mostly to north temperate areas of Europe, Asia and North America. Nomenclature is difficult and confusing within the genus making plant identification between species difficult. However, willows have several morphological characteristics in common including leaves, buds and flowers. Salicaceae Salix sp. – Willow Willow leaves are simple and alternate and usually lanceolate in shape. The leaf margin has salicoid teeth where the veins terminate in a gland. Gland Salicaceae Salix sp. – Willow The buds of willow are covered by a single bud scale. Flower bud Vegetative bud Salicaceae Salix sp. – Willow Willow produces male or female flowers in catkins usually on separate plants. Each individual flower lacks sepals and petals and is subtended by a bract beside one or two glands. Each female flower usually has two carpels and most male flowers usually have two stamens (some species have up to 12 stamens). Male flowers Female flowers Stigma Stamens Bract Glands Glands Bract Salicaceae Salix sp. – Willow It is the silvery hairs on the bracts of individual male flowers that give the opening buds the “pussy willow” appearance. Salicaceae Salix sp. – Willow Fruits are a two-valved capsule that opens to release seeds covered with long silky hairs. Capsule Seeds Capsules Seeds Salicaceae Salix alba – White willow White willow and its hybrids are the most widely used willows in U.S. landscapes. It is a large deciduous tree used mostly as a specimen tree. White willow is especially attractive planted along side water. Native from Central Europe to Central Asia. Salicaceae Salix alba – White willow Growth habit – An upright growing tree forming a rounded crown at maturity. Limbs branch low on the trunk and the branches are flexible. Tree size – Fast-growing trees can reach 70 or more feet tall. Salicaceae Salix alba – White willow Culture: Full sun. Trees are adaptable but thrive in moist soils and will tolerate brief periods of flooding. Plants are susceptible to a number of foliar and stem diseases and are weakwooded. Hardy in zones 8 to 2. Salicaceae Salix alba – White willow Cultivars: ‘Britzensis’ – Stems are bright orange red. Plants can be cut back each year to accentuate this feature. Salicaceae Salix alba ‘Tristis’ – Golden weeping willow Cultivars: Golden weeping willow (‘Tristis’) is the most common weeping willow in U.S. commerce. Nomenclature is confused concerning the weeping willows and nurseries may sell the same plant as Salix alba ‘Niobe’, Salix alba ‘Vitellina Pendula’ or Salix babylonica (Babylon weeping willow). Salicaceae Salix alba ‘Tristis’ – Golden weeping willow Growth habit – Main branches are ascending while the secondary branches are pendulous sometimes reaching the ground. Tree size – Usually to approximately 60 feet tall, but can reach over 100 feet tall with age. Salicaceae Salix alba ‘Tristis’ – Golden weeping willow The leaves are the typical lanceolate shape and the yellow stems are suggestive of the common name golden weeping willow. Salicaceae Salix alba ‘Tristis’ – Golden weeping willow Golden weeping willow makes a wonderful companion specimen on the edge of ponds. Salicaceae Salix alba ‘Tristis’ – Golden weeping willow Its pendulous habit provides an elegant architectural feature to landscapes. Salicaceae Salix alba ‘Tristis’ – Golden weeping willow In the morning mist, golden weeping will adds an evocative element to a landscape. Salicaceae Salix alba ‘Tristis’ – Golden weeping willow In this design, the weeping branches frame a bridge along a garden pathway. Salicaceae Salix alba ‘Tristis’ – Golden weeping willow Weeping willow is an essential design element near water in a Chinese garden landscape. It helps to frame key structures and define outdoor rooms.
