Yellow False Acacia, Black Locust, Yellow Locust 'Purple Robe'


Family: Papilionaceae (pa-pil-ee-uh-NAY-see-ee) (Info)
Genus: Robinia (roh-BIN-ee-uh) (Info)
Cultivar: Purple Robe



Foliage Color:

Unknown - Tell us

Bloom Characteristics:

This plant is attractive to bees, butterflies and/or birds

Flowers are fragrant

Water Requirements:

Drought-tolerant; suitable for xeriscaping

Where to Grow:

Unknown - Tell us


30-40 ft. (9-12 m)

over 40 ft. (12 m)


20-30 ft. (6-9 m)


USDA Zone 4a: to -34.4 C (-30 F)

USDA Zone 4b: to -31.6 C (-25 F)

USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

Sun Exposure:

Full Sun


Seed is poisonous if ingested

Parts of plant are poisonous if ingested

Bloom Color:


Bloom Time:

Late Winter/Early Spring

Mid Spring

Late Spring/Early Summer


Grown for foliage



Other details:

Unknown - Tell us

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

7.6 to 7.8 (mildly alkaline)

Patent Information:


Propagation Methods:

From hardwood cuttings

From seed; direct sow outdoors in fall

Seed Collecting:

Allow pods to dry on plant; break open to collect seeds

Seed does not store well; sow as soon as possible


This plant has been said to grow in the following regions:

Kearny, Arizona

Prescott, Arizona

Yarnell, Arizona

Acton, California

Arcata, California

Banning, California

Chowchilla, California

Felton, California

Redlands, California

San Jacinto, California

Simi Valley, California

Walnut Creek, California

Denver, Colorado

Fort Collins, Colorado

Thayer, Illinois

Winnetka, Illinois

Pocomoke City, Maryland

Upper Marlboro, Maryland

Buchanan, Michigan

Stephenson, Michigan

La Luz, New Mexico

Las Cruces, New Mexico

Roswell, New Mexico

Hereford, Texas

Ivins, Utah

Payson, Utah

Lexington, Virginia

show all

Gardeners' Notes:


On Mar 8, 2014, coriaceous from ROSLINDALE, MA wrote:

This is not a cultivar of Robinia pseudoacacia. It is 3/4 R. hispida.

This cultivar is a hybrid Robinia x ambigua, the product of a deliberate cross between R. x ambigua 'Decaisniana' and R. hispida 'Monument'.

"Purple Robe TM" is the trademark. Cultivar names cannot legally be trademarked. What this taxon's cultivar name seems to be a mystery.

Described as thornless, but it's been said that some specimens develop thorns.

It isn't invasive in the US southwest. Commercially propagated stock are likely to be grafted on seed-grown R. pseudoacacia understock. The understock is invasive when grown outside its native range in eastern and midwestern North America, and is prohibited in Massachusetts.


On Jun 3, 2013, agchicago from Chicago, IL wrote:

I have two trees in different areas on my farm in SW Michigan. They are beautiful compact trees, with wonderful smelling flower clusters in late spring. Young branches are covered in red hairs, approximately 1cm long. They look like they would be sharp as a cactus needle, but they aren't. They are very unusual and great to look at year round. Both trees are in partial shade, which I think may be key to containing their growth. Neither of the ones I have are aggressively propagating whatsoever, so take others comments with a grain of salt, your results may vary. The two on my property have been there for at least 20 years that I know of.


On May 27, 2013, weedsfree from Magna, UT (Zone 7a) wrote:

I have not grown this tree for myself but I want to. There are 2 of the purple blooming ones and 1 white blooming one down the street from me. One of the purple blooming ones is severely damaged and sick looking. The other 2 are on the same property but very healthy. Over the years I have never ever seen them sucker. That is a big plus for me. Nor have I ever seen new seedlings from the dropped seeds. They are growing in a spot on this property that is clearly seen without trespassing. I love the look of the large snapdragon type blooms and I love the smell of grapes they put off. Now that I know what they are, I can do research on them and get me some! They do seem slow growing however.


On Apr 16, 2013, palmbob from Acton, CA (Zone 8b) wrote:

Sad so many negatives, but I guess in other climates this plant is a nuisance... but here in the high deserts of California where few other things grow at all, this plant is amazing- adding some color where there simply is none, and growing without any supplemental water all year round (save the 2-4 inches we get in the winter)... handles high winds (it's windy EVEry day here, sometimes over 75mph), extremes in temp (summers here over 100 nearly every day, and snows in the winter), and looks great in early spring in full bloom. NO way is this invasive here.. in fact, I have never even seen it sucker here. One of the most attractive trees that one can grow in sunset garden zone 11.


On Mar 15, 2008, distantkin from Saint Cloud, MN (Zone 4b) wrote:

Black locust (Robinia pseudoacacia) is considered invasive by the Minnesota DNR
"Ecological Threat:

* Invades primarily disturbed habitats, degraded wood, thickets and old fields crowding out native vegetation of prairies, oak savannas and upland forests, forming single species stands.
* It reproduces vigorously by root suckering and stump sprouting forming a common connecting root system.
* It is native to the U.S. and occurs naturally on the lower Appalachian mountain slopes. It has been extensively planted for its nitrogen-fixing qualities and its hard wood."


On Aug 2, 2007, lyndy_1 from Kearny, AZ wrote:

We first saw this plant at Superstition Springs Mall in Mesa AZ. Trees line the lanes throughout the parking areas. I saw clusters of the seeds and grabbed a few to try. I've had the pink honey locust trees in CA. I'm going to plant the seeds and see what happens. We live East of Mesa, In Kearny. Wish me luck!


On Jul 11, 2007, cactuspatch from Alamogordo, NM (Zone 7b) wrote:

This tree is really pretty when in bloom. However the scent is strong and I am highly allergic to it. It was a bit fragile and was topped by a high wind, which caused it to die. Even though we dug it out 2 years ago, I am constantly cutting off the new shoots it is sending up, apparently from the roots that weren't dead? I would never plant this tree again. One short season of beautiful blooms is not work all the trouble it has caused. I now have a beautiful crepe myrtle in its place, long beautiful bloom, no disgusting scent to cause headaches for weeks, and no plants coming up all over the place.


On Mar 16, 2007, Bledsoe from Fort Collins, CO wrote:

Although suckering, and water spouts do frequently happen to this tree, it's absolutely a beautiful tree when flowers are in bloom. This tree can also be grown where most trees can't grow. Also when full grown has a great canvas


On Oct 24, 2005, Dianesgarden from Walnut Creek, CA wrote:

This cultivar is invasive, sending out additional underground shoots every year. These shoots grow into new trees and are resistant to pruning at ground level or digging up.