Evergreen Ornamentals: Coniferous Evergreens (Hort 1008)

A comprehensive set of flashcards covering key concepts and characteristics of coniferous evergreens, specifically focusing on various species within the Picea and Tsuga genera.

What is the scientific name for Norway spruce?

Picea abies.

What are the identification characteristics of Picea trees?

Evergreen, broadly conical to thin and spire-like, with needle-like foliage attached to a leaf peg.

What is a common issue with spruce trees regarding their root systems?

Spruce trees can be very susceptible to windthrow due to their shallow root systems.

What is the leaf shape of Picea abies?

Needle-like, ½-1" long, four-sided, stiff, and slightly curved.

What is the habitat origin of Picea glauca (white spruce)?

Canada and northern United States.

What are the landscape uses for Picea glauca?

Specimen, screening, windbreaks, and Christmas tree.

What is the form of Picea omorika (Serbian spruce)?

Pyramidal; narrow at top with short arching branches.

What advantages do Picea trees have regarding transplanting?

They can be easily transplanted in large sizes due to shallow spreading root systems.

What is a significant potential problem for Picea pungens var. glauca (Colorado blue spruce)?

Susceptibility to spruce spider mites, spruce gall adelgid, and spruce budworm.

What distinguishes the needles of Tsuga canadensis (Canadian hemlock)?

Needles are small, flat, glossy green with glaucous undersides and two prominent white stomata bands.

Provide a list of botanical and common names for the conifers studied in Units 1 and 2.

1. $Picea\ abies$ - Norway Spruce

2. $Picea\ glauca$ - White Spruce

3. $Picea\ glauca\ 'Conica'$ - Dwarf Alberta Spruce

4. $Picea\ omorika$ - Serbian Spruce

5. $Picea\ pungens\ var.\ glauca$ - Colorado Blue Spruce

6. $Tsuga\ canadensis$ - Canadian Hemlock

7. $Abies\ concolor$ - White Fir

8. $Pseudotsuga\ menziesii$ - Douglas Fir

Which of the conifers from Units 1 and 2 are native to Canada?

1. $Picea\ glauca$ (White Spruce)

2. $Tsuga\ canadensis$ (Canadian Hemlock)

Categorize the botanical names for conifers by their growth rates (slow, medium, and fast).

• Slow: $Picea\ glauca\ 'Conica'$, $Picea\ pungens\ 'Glauca\ Globosa'$

• Medium: $Picea\ pungens\ var.\ glauca$, $Picea\ omorika$, $Tsuga\ canadensis$

• Fast: $Picea\ abies$, $Pseudotsuga\ menziesii$

Which conifers have silver-blue foliage?

1. $Picea\ pungens\ var.\ glauca$ (Colorado Blue Spruce)

2. $Abies\ concolor$ (White Fir)

List the botanical names for conifers that are particularly susceptible to pests or diseases.

1. $Picea\ pungens\ var.\ glauca$ (Canker, needle cast, mites)

2. $Picea\ glauca\ 'Conica'$ (Spider mites)

3. $Tsuga\ canadensis$ (Hemlock woolly adelgid)

Describe the leaf colour of $Picea\ omorika$.

Glossy dark green on the upper surface with two prominent white stomatal bands on the lower surface, giving it a bicolor or silvery appearance.

What is the most widely planted spruce tree in North America?

$Picea\ abies$ (Norway Spruce).

What is a common pest of $Picea\ glauca\ 'Conica'$ and what damage does it cause?

Spruce spider mites. They cause bronzing or browning of the needles, which may eventually drop, often starting from the inner foliage.

List 3 characteristics of the genus $Picea$.

1. Needles are attached to woody peg-like projections (pulvini).
2. Needles are usually 4-sided (square in cross-section).
3. Cones are pendulous (hang downwards) and have thin, papery scales.

List 3 characteristics of the genus $Abies$.

1. Needles are flat and attached by a base that looks like a small suction cup (discoid scar).
2. Cones are held upright on the branches.
3. Cones shatter upon maturity, leaving only the central axis.

List 3 characteristics of the genus $Tsuga$.

1. Needles are flat and narrow with a distinct petiole.
2. Needles typically have two white stomatal bands on the underside.
3. The leading shoot (apex) characteristically droops.

Which tree species can be transplanted in large sizes and why?

Spruce trees ($Picea$ species). This is possible because they possess shallow, spreading root systems that allow for a large root ball to be harvested.

List 3 characteristics of the genus $Pseudotsuga$.

1. Buds are long, reddish-brown, and sharply pointed.
2. Cones have prominent three-lobed 'fork-like' bracts protruding from the scales.
3. Needles are flat and arranged spirally but often appear two-ranked.

What pest causes devastating losses in Canadian Forests?

Spruce Budworm ($Choristoneura\ fumiferana$).

What is reversion? List a conifer that may experience this.

Reversion occurs when a dwarf or variegated cultivar produces a shoot with the characteristics of the original species (e.g., vigorous growth or green foliage). $Picea\ glauca\ 'Conica'$ is known to occasionally revert to vigorous white spruce growth.

What is a topiary?

The horticultural practice of training live perennial plants by clipping the foliage and twigs of trees and shrubs to develop and maintain clearly defined shapes, whether geometric or fanciful.

What is a standard? List one species grafted to grow as a standard.

A standard is a plant trained to have a single tall, clear stem (trunk) with a rounded or weeping head of foliage. Example: $Picea\ pungens\ 'Glauca\ Globosa'$ is often grafted onto a upright stem to create a standard.

True or False: $Picea\ abies\ 'Nidiformis'$ has scale-like foliage.

False. It has needle-like foliage typical of the species.

True or False: All evergreens reproduce by cones.

False. While many do (conifers), some evergreens like Yews ($Taxus$) produce berry-like structures called arils, and broadleaf evergreens produce fruit.

What two parts combine to make the botanical name?

The Genus and the specific epithet.

Which species from units 1 & 2 tolerate part-shade locations?

$Tsuga\ canadensis$ (Canadian Hemlock).

Compare the form and foliage of $Picea\ omorika$ to $Tsuga\ canadensis$.

• Form: $Picea\ omorika$ is narrowly pyramidal with arching branches; $Tsuga\ canadensis$ is broadly pyramidal with a drooping leader.
• Foliage: $Picea\ omorika$ has 4-sided but flattened needles; $Tsuga\ canadensis$ has distinctly flat, petiolate needles that are smaller and more delicate.

What does the specific epithet 'pungens' mean?

Sharp-pointed or piercing (referring to the needles).

Name a plant variety that will guarantee you excellent blue foliage.

$Picea\ pungens\ 'Hoopsii'$ or $Picea\ pungens\ 'Fat\ Albert'$.

Describe the form of $Tsuga\ canadensis$.

Pyramidal with a graceful, fine-textured appearance and a characteristic drooping leading shoot.

What signs should you look for to know if a tree has hemlock woolly adelgid?

Search for white, woolly, cotton-like masses at the base of the needles on the underside of the twigs.

Which cultivar of $Tsuga\ canadensis$ will provide a pendulous/weeping form?

$Tsuga\ canadensis\ 'Sargentii'$ (Sargent's Weeping Hemlock).