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Ironwood Tree: Facts, Leaves, Flowers, Bark (Image) - Identification & Care

Ironwood Tree: Facts, Leaves, Flowers, Bark (Image) - Identification & Care


Ironwood (  Ostrya virginiana  ) is a small deciduous tree of the understory. It is recognized by its birch-like leaves, light brown hairy bark and yellowish-green flowers. Ironwood trees are attractive in the landscape with their pyramidal rounded crown and ability to grow almost anywhere. As an understory tree, ironwood does well in deep shade, and it grows equally well in full sun. 


Ironwood, also called  American hornbeam  , is known for its incredibly strong, durable wood, which is a result of its slow growth. An attractive frost-resistant tree grows well on slopes, as well as stony forests, compacted clay soil, relatively resistant to drought.

This article is a complete guide to ironwood identification. Descriptions and images of ironwood leaves, bark, flowers, and fruit will help you identify it in the landscape. If you decide that this tree is perfect for your garden landscape, there is a handy care guide at the end of the article.

Ironwood (  Ostrya virginiana  ) Facts

Граб американський (Ostrya virginiana)

American hornbeam (Ostrya virginiana)

Zaliznyak is classified as a small or medium-sized ornamental tree belonging to the  Ostrya genus of the Betulaceae  birch family   . Ironwood grows 20 to 40 feet (6–12 m) tall and up to 30 feet (9 m) wide. It has a trunk diameter of up to 10 inches (25 cm), covered with scaly, shaggy bark. 

Ironwood trees grow slowly, averaging about 12 inches (30 cm) or less per year. It takes 15 years to grow 10-15 feet (3-4.5 m) tall. Young cast irons have a typical pyramidal shape that gradually becomes more oval and rounded as they mature. 

Ironwood trees thrive in USDA hardiness zones 3 through 9. This hardy tree does well in all growing conditions, from deep shade to full sun. As long as the soil is well-drained and not prone to flooding, ironweed grows well in most soils.

An attractive feature of ironwood trees is their horizontal, drooping branches covered with toothed, egg-shaped leaves. Immature trees have somewhat fuzzy branches that become smoother and grayer as the tree matures. 

The slow growth of ironwood trees is why the wood is so strong. Ironwood has one of the hardest woods of any native North American tree. It is heavier than  maple  , white oak, hickory, elm and  birch  . Because of this, the wood is used to make tool handles, fence posts, and mallets. 

Other common names for ironwood   refer to the tree's strength or growth characteristics. For example, the names American hop and woolly hornbeam refer to the hop-like fruits that the tree produces after flowering. It is also sometimes called leverwood or hardhack.

As a member of the birch family  Betulaceae  , ironwood shares characteristics of birch and  elm  . Its leaves are spear-shaped with serrated edges, like those of birch. In addition, its sprawling pyramidal or oval shape gives it the appearance of elms. However, ironwood trees are much smaller than elm and birch.

Iron tree flowers

Остря віргінська квіти

Iron tree flowers

Flowers on iron trees have the form of drooping bunches - yellowish-green or reddish-brown drooping bunches. The tubular clusters are about 3 inches (75 mm) long and grow in groups of up to four. Ironwood is a monoecious tree, meaning male and female flowers appear on the same tree.

The male flowers of ironwood are yellowish brown and look like scaly spikes hanging from the branches. On the other hand, the female flowers of ironwood are pale green spikes that stand directly on new twigs. 

The peculiarity of iron tree flowers is that men's earrings are kept on the tree all winter. 

Iron tree leaves

Листя дерева залізного дерева

Iron tree leaves

Ironwood leaves are light green, lanceolate with double serrated edges and a fine fuzzy texture on the upper side. The oval  -elliptic pointed leaves  are 3 to 6 inches (75-150 mm) long and 2 inches (50 mm) wide. Ironwood leaves are characterized by deep parallel ribs from the midrib to the margin.

Ironwood leaves are simple leaves that grow alternately on thin twigs. Pointed spear-shaped blades, as a rule, are small further up the canopy.

залізне дерево осіннє листя

Iron tree leaves in autumn

Iron tree leaves are easily confused with birch leaves. However, ironwood leaves turn a slight yellow color in autumn compared to the bright golden-yellow leaves of birch. Also, ironwood leaves usually fall earlier than birch leaves. 

Iron tree bark

Остря віргінська кора

Iron tree bark

The bark covering the trunk of the ironwood is light brown and hairy, developing into rectangular plates. Bark on young iron trees is relatively smooth with a few lenticels. However, over time the bark peels and easily peels off the tree. Adult ironflies have grayish-brown loose scaly plates. 

Iron Tree Seeds (Fruit)

Насіння залізного дерева (фрукти)

Fruits of the iron tree

The ironwood tree is recognizable by its hop-like fruits—clusters of papery sac-like seed pods, each containing a tiny oval nut. Suspended clusters of papery bodies grow 1 to 2 inches (25 to 50 mm) in length. Clusters of seeds develop in the summer and are stored on the tree during the winter. 

Identification of ironwood

The identifying features of the ironwood tree are its light green pointed lance-shaped leaves with doubly serrated edges, drooping copper-brown hop-like fruits, and light-dark brown hairy narrow strips of bark. Ironwood is a relatively small tree in the landscape compared to birch and elm. 

Iron trees in the landscape

Ironwood is an attractive shade-tolerant tree, making it ideal for growing as an understory. Ironwood does well in a variety of moisture and soil conditions, but grows best in well-drained soil in partial sun. In the landscape, the ironwood has a rounded canopy and a thin, rough trunk. 

Ironwood is an excellent tree for growing in urban and residential landscapes. The hardy tree copes well with various urban conditions such as pollution and compacted soil. This is one of the reasons why it is a popular street tree. Additionally, the tree's relatively small size makes it ideal for residential gardens to grow as a shade tree in the backyard or around patios, especially where space is limited.

One of the reasons for growing ironwood is that it needs little pruning to keep it in shape. In addition, its strong branching system means it is resistant to breakage in high winds or under heavy ice or snow.  

Where to plant an iron tree

Ironwood trees are best planted in sun to partial shade. However, as an attractive upright understory tree, it also grows well in deep shade. Ironwood also adapts well to different soil conditions. Therefore, you can plant it in dry, gravelly soil or heavily compacted clay soil. 

When planting an ironwood, the most important point of cultivation is that the soil drains well. The virginia sedge  does not like soggy roots, and it does not grow well in places prone to flooding. 

Another factor is its tolerance to salty conditions. Ironwood does not tolerate salt well, so it should not be planted near roads that are heavily salted in winter.

How to plant an iron tree

Ironwood is best planted as a container grown nursery. Ironwood trees are notoriously slow growing, and planting a tree from a nursery gives you a great advantage. 

To plant  Ostrya virginiana  in a pot, prepare the site by digging a hole as deep as the root ball but three times as wide. Then remove the tree from the pot and loosen the roots as much as possible. Then set it in the center of the hole, making sure that the part where the trunk extends to the roots (the growth of the tree) is slightly above ground level.

The next step is to fill the hole halfway with native soil, firmly tamping the soil as you backfill the site. Then water the roots thoroughly to moisten them and eliminate air pockets. Finally, fill the hole up to the soil line, pressing as you go. 

After planting an ironwood, water the soil thoroughly and apply a  2-3 inch (5-7.5 cm) layer of mulch over the root area. Mulching a newly planted tree helps retain moisture, prevents evaporation, and prevents weed growth. 

Ironwood (  Ostrya virginiana) Care Guide  .

Iron trees are easy to care for as they can adapt to different environmental conditions. However, to obtain the best results, iron-resistant trees require special care, especially in the first years after planting. On the other hand, iron trees, which have proven themselves well, tolerate drought and do not require special care.

How to Water Ironwood Trees

Established ironwood trees do not require much watering for healthy growth. As a general rule, you can give the tree about 1 inch (25 mm) of water per week as long as the topsoil dries out between waterings. However, ironwood trees are relatively  drought tolerant  and  can withstand periods of dry conditions. 

Regular watering is important for the first two years after planting an ironwood tree. Regular watering of the roots promotes the development of a healthy and strong root system. During the first two years, water the tree abundantly twice a week, from spring to summer. In addition, it may be necessary to water the tree more often, especially in dry weather. 

Iron tree fertilizer

Ironwood trees  can benefit from regular fertilizing  to keep them healthy and prevent pest damage—but it's not usually necessary. You can use a fertilizer rich in nitrogen to promote the growth of green leaves. It is important to avoid excess nitrogen in the soil as this can affect flower and seed production. 

As a general rule, there is no need to amend the soil or apply fertilizer to newly planted ironwood trees. This is explained by the fact that the salts in the fertilizer can burn the roots. 

It is good to note that ironwood usually grows well in average soil without the addition of fertilizers. The best advice is to treat the root area with rotted manure or organic compost in the spring. However, if you decide that your tree needs additional nutrients, first do a soil test to determine the type of fertilizer for your tree. 

How to cut an iron tree

Ironwood does not require heavy pruning to develop a strong branch structure. While the tree is relatively young, you can remove some side branches to form a dominant central trunk. This is especially necessary for some ironwood trees that grow in multiple stems. However, an established ironwood does not require regular pruning.

As part of regular tree care, it's a good idea to do an annual inspection of ironwood trees in late fall after the leaves have fallen. Look for broken, dead, or diseased limbs, as well as branches that are rubbing against each other. You can remove these branches to promote healthy growth and prevent disease. 

Reproduction of the iron tree

Although stem cuttings are the most common method of propagating shrubs and trees, seed propagation is the preferred method of growing ironwood. Ironwood requires warm and cold stratification for successful seed germination. 

It is worth noting that gloves should be worn when working with ironwood seeds. The ornamental tree is also called  an itchy tree  because the accumulation of seeds can cause itchy fingers — for example, after using fiberglass insulation without protection.

How to grow an iron tree from seed

Ironwood trees are relatively easy to grow from seed by sowing them directly into the ground in early fall. 

Alternatively, you can collect ripe seeds between late summer and early fall and dry them. 

Ironwood seeds require 60 days of warm stratification followed by 120-140 days of cold stratification. This is necessary for successful germination.  Here's what you need to do  to grow  Ostria virginska from seeds:

  • Immerse the seeds in a jar of boiling water and leave them for 24 hours.
  • Place the seeds in a resealable plastic bag filled with moist sphagnum moss. 
  • Place the seeds in a warm place with a temperature of 68°F to 86°F (20°C to 30°C) for 60 days. Then check the seeds regularly for mold and keep the soil slightly moist.
  • After that, place the bag in a cool place between 39°F and 41°F (4°C - 5°C) (like your refrigerator) for 120 days.

After stratifying the seeds, you can place the seeds in small pots filled with moist, well-drained soil to germinate using standard procedures. 

How to grow Ironwood seedlings

To germinate stratified ironwood seeds, prepare a seed soil mix of 3 parts  peat moss  and one part  perlite  . Fill small individual pots with potting mix and misting mist. Then place the seeds in each pot about 0.25 inches (6 mm) below the surface, cover with plastic wrap, and place in a bright, warm location out of direct sunlight.

When the seeds germinate after a few weeks, place them in a brighter location where they get about 12 hours of light each day. After a month, you will need to transplant the ironwood seedlings into a larger pot. You can then plant them outdoors in the ground when the seedlings are about 15-20 inches (40-50 cm) tall.

Pests affecting the growth of ironwood

An advantage of growing ornamental ironwood in the landscape is that it is relatively pest free. Healthy trees rarely suffer from common wood bugs such as aphids,  scale insects  or leafhoppers. 

The only significant pest that affects ironwood leaves is the chestnut borer (  Agrilus bilineatus  ). This  slender black beetle  can live and feed on the inner bark of ironwood. Beetle activity can lead to defoliation. However, the best way to prevent this is to water ironwood well during periods of drought. 

Diseases affecting ironwood tree growth

Ironwood is a strong, hardy tree, and typical tree diseases rarely affect its growth. Sometimes ulcer diseases can lead to the death of individual branches. However, this can usually be avoided by preventing stress on the tree. Therefore, water well in dry weather. 

Occasionally, foliar diseases such as powdery mildew, blistering, and leaf spot can affect tree leaves. However, they never cause significant damage to the health of the tree, and there is no need to deal with them at all.

Link: https://leafyplace.com/ironwood-tree/


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