In the past, Robinia pseudoacacia was used extensively for shipbuilding. Today it is used for posts, mine timbers, fuel, pulp, and nectar production for honey. In addition, it is used in construction, landscaping, and erosion control. Although it is native to the United States, it has been introduced outside of its native range, becoming invasive in some areas.
Black locust is a deciduous tree growing 40 to 80 feet tall or more. Small, white flowers having both male and female parts are grouped into showy, fragrant, hanging clusters. Flowering begins when the plant reaches maturity at approximately 6 years of age. Flowers are insect-pollinated.
Black locust grows in canyons, open woods, floodplains, pastures, and abandoned homesites, and on roadsides, slopes, streambanks, and riparian sites. Although it grows in a wide range of soil types, it prefers sites that have deep, rich, moist but well-drained soils derived from limestone. It does not do well on poorly drained or excessively dry soils. It is intolerant of shade, but tolerates drought.
Black locust is a USA-NPN regional plant species. Regional species are ecologically or economically important and are distributed more locally than calibration species. The NPN integrates these observations to better understand plant responses within the different geographic regions of the nation. In addition, this species is an allergen. Observations on its phenology will provide valuable information to benefit people with allergies and the public health community. Also, this species is potentially invasive. Observations on its phenology will provide valuable information toward understanding its potential for spread and its control. The NPN does not promote planting or cultivation of this or any invasive plant.
If drought seems to be the cause of leaf color or fall for a plant, please make a comment to that effect.
Do you see...?
Breaking leaf buds One or more breaking leaf buds are visible on the plant. A leaf bud is considered "breaking" once a green leaf tip is visible at the end of the bud, but before the first leaf from the bud has unfolded to expose the leaf stalk (petiole) or leaf base.
How many buds are breaking?
Less than 3
3 to 10
More than 10
Leaves One or more live unfolded leaves are visible on the plant. A leaf is considered "unfolded" once the leaf stalk (petiole) or leaf base is visible. New small leaves may need to be bent backwards to see whether the leaf stalk or leaf base is visible. Do not include dried or dead leaves.
What proportion of the canopy is full with leaves?
Less than 5%
5-24%
25-49%
50-74%
75-94%
95% or more
Increasing leaf size A majority of leaves on the plant have not yet reached their full size and are still growing larger. Do not include new leaves that continue to emerge at the ends of elongating stems throughout the growing season.
What proportion of full size are most leaves?
Less than 25%
Colored leaves One or more leaves (including any that have recently fallen from the plant) have turned to their late-season colors.
What proportion of the canopy is still full with green leaves?
Falling leaves One or more leaves are falling or have recently fallen from the plant. More...
Flowers One or more fresh flowers or flower heads (inflorescences) are visible on the plant. Flower heads include many small flowers that usually do not open all at once. Do not include wilted or dried flowers that remain on the plant, or heads whose flowers have all wilted or dried.
How many fresh flowers or flower heads are present?
Open flowers One or more open fresh flowers are visible on the plant. Flowers are considered "open" when the reproductive parts (male stamens or female pistils) are visible between unfolded or open flower parts. Do not include wilted or dried flowers that remain on the plant.
How many fresh flowers are open?
Peak flower: The plant has a large number of flowers and one half (50%) or more are open and still fresh.
Fruits One or more fresh fruits are visible on the plant.
How many fresh fruits are present?
Ripe fruits One or more ripe fruits are visible on the plant.
How many fruits are ripe?
Recent fruit drop One or more fresh mature fruits or seeds have dropped or been removed from the plant since your last visit. Do not include obviously immature fruits that have dropped before ripening, such as in a heavy rain or wind.
How many mature fruits have dropped?
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