A detailed list of the 50 most common trees and shrubs in Calgary and Southern Alberta requires acknowledging both native and commonly planted species. Here's an overview:

Trees:

1. Swedish Columnar Aspen (Populus tremula 'Erecta') - Known for its narrow, vertical growth, ideal for small spaces.

2. Colorado Blue Spruce (Picea pungens) - Features blue-green needles, making it a popular ornamental choice.

3. Norway Spruce (Picea abies) - Dense, evergreen, used for privacy screens and windbreaks.

4. Trembling Aspen (Populus tremuloides) - Native, known for leaves that flutter in the wind.

5. Amur Maple (Acer ginnala) - Small, with brilliant fall colours, suitable for smaller landscapes.

6. Evans Cherry (Prunus pensylvanica 'Evans') - Hardy cherry tree, produces sweet cherries.

7. Ure Pear (Pyrus ussuriensis 'Golden Spice') - Hardy pear with sweet fruit, good for small gardens.

8. Ohio Buckeye (Aesculus glabra) - Offers spring flowers and spectacular fall foliage.

9. Bur Oak (Quercus macrocarpa) - Large, native oak with distinctive acorns.

10. Green Ash (Fraxinus pennsylvanica) - Fast-growing but now threatened by Emerald Ash Borer.

11. White Spruce (Picea glauca) - Cold-hardy, often used for reforestation.

12. Russian Olive (Elaeagnus angustifolia) - Silver foliage, drought-resistant, invasive tendencies.

13. Saskatoon (Amelanchier alnifolia) - Native, produces edible berries.

14. Mayday Tree (Prunus padus) - Showy white flowers, can become invasive.

15. Tower Poplar (Populus x canescens 'Tower') - Fast-growing, narrow form for privacy.

16. Black Hills Spruce (Picea glauca var. densata) - Similar to White Spruce but denser.

17. Dolgo Crab Apple (Malus 'Dolgo') - Hardy, produces fruit for jelly.

18. September Ruby Apple (Malus 'September Ruby') - Late-season apple with good flavor.

19. Royalty Flowering Crab (Malus 'Royalty') - Dark foliage, red fruit.

20. Brandon Elm (Ulmus americana 'Brandon') - Dutch elm disease resistant, good shade tree.

21. Laurel Leaf Willow (Salix pentandra) - Fast-growing, used for soil erosion control.

22. Morden Amorette Rose (Rosa 'Morden Amorette') - Ornamental rose with pink flowers.

23. Chokecherry (Prunus virginiana) - Native, with dark, tart berries.

24. Shubert Chokecherry (Prunus virginiana 'Shubert') - Purple foliage, edible fruit.

25. Hawthorn (Crataegus spp.) - Various species, valued for spring blooms.

26. Lombardy Poplar (Populus nigra 'Italica') - Tall, narrow, but short-lived.

27. Golden Willow (Salix alba 'Vitellina') - Known for its yellow twigs in winter.

28. Siberian Larch (Larix sibirica) - Deciduous conifer, golden fall color.

29. Manitoba Maple (Acer negundo) - Also called Box Elder, native and hardy.

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Shrubs:

30. Cotoneaster (Cotoneaster spp.) - Shrubs or small trees, red berries in fall.

31. Caragana (Caragana arborescens) - Hardy, often used for hedges.

32. Potentilla (Potentilla fruticosa) - Low-growing, with yellow flowers.

33. Saskatoon Serviceberry (Amelanchier alnifolia) - Similar to the tree form but shrub-like.

34. Buffaloberry (Shepherdia argentea) - Silver foliage, red berries.

35. Lilac (Syringa vulgaris) - Common for its fragrant spring flowers.

36. Ninebark (Physocarpus opulifolius) - Striking foliage, native to North America.

37. Red Osier Dogwood (Cornus sericea) - Known for red stems in winter.

38. Cranberry Cotoneaster (Cotoneaster apiculatus) - Low-growing with red berries.

39. Honeysuckle (Lonicera spp.) - Various species, some native, some invasive.

40. Mock Orange (Philadelphus lewisii) - Native, fragrant white flowers.

41. Rugosa Rose (Rosa rugosa) - Hardy with large, fragrant blooms.

42. Juniper (Juniperus spp.) - Various types used for ground cover or small trees.

43. Spirea (Spiraea spp.) - Popular for their flowering clusters.

44. Elderberry (Sambucus canadensis) - Native with edible berries.

45. Wolf Willow (Elaeagnus commutata) - Silvery leaves, yellow flowers.

46. Rabbitbrush (Chrysothamnus nauseosus) - Native, golden-yellow flowers.

47. Bearberry (Arctostaphylos uva-ursi) - Low-growing, good for ground cover.

48. Sagebrush (Artemisia tridentata) - Native, aromatic, silver foliage.

49. Golden Currant (Ribes aureum) - Yellow flowers, edible berries.

50. Rose Hip (Rosa spp.) - Various wild roses, known for their hips.

Each of these plants has adaptations that make them suitable for Calgary's and Southern Alberta's often harsh climate, including cold winters, hot summers, and variable precipitation. However, some species like Russian Olive are noted for their invasive potential, which should be managed carefully. Also, species like Green Ash face threats from pests, affecting their prevalence in new plantings.

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