Stachytarpheta Species, Blue Porterweed, Blue Rat's Tail, Cayenne Snakeweed

Stachytarpheta cayennensis

Family: Verbenaceae (ver-be-NAY-see-ee) (Info)
Genus: Stachytarpheta (stay-kee-tar-FEE-tuh) (Info)
Species: cayennensis (kae-yen-EN-sis) (Info)
Synonym:Stachytarpheta australis
Synonym:Stachytarpheta dichotoma
Synonym:Stachytarpheta gibberosa
Synonym:Stachytarpheta hirta
View this plant in a garden



Tropicals and Tender Perennials

Water Requirements:

Drought-tolerant; suitable for xeriscaping

Sun Exposure:

Light Shade

Partial to Full Shade



Foliage Color:



4-6 ft. (1.2-1.8 m)


24-36 in. (60-90 cm)


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

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

USDA Zone 10a: to -1.1 C (30 F)

USDA Zone 10b: to 1.7 C (35 F)

USDA Zone 11: above 4.5 C (40 F)

Where to Grow:

Grow outdoors year-round in hardiness zone


Unknown - Tell us

Bloom Color:

Medium Blue

Bloom Characteristics:

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

Bloom Size:

Unknown - Tell us

Bloom Time:

Blooms all year

Other details:

May be a noxious weed or invasive

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

Patent Information:


Propagation Methods:

From seed; direct sow outdoors in fall

Seed Collecting:

Unknown - Tell us


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


Bartow, Florida

Big Pine Key, Florida

Bokeelia, Florida

Boynton Beach, Florida

Bradenton, Florida

Brandon, Florida

Brooksville, Florida

Cape Coral, Florida (2 reports)

Englewood, Florida

Fort Lauderdale, Florida

Gainesville, Florida

Gulf Breeze, Florida

Hollywood, Florida

Homosassa, Florida

Hudson, Florida

Jacksonville, Florida (2 reports)

Keystone Heights, Florida

Lake Butler, Florida

Lake Worth, Florida

Largo, Florida

Longboat Key, Florida

Longwood, Florida

Lutz, Florida

Melbourne, Florida

Miami, Florida

Palm Coast, Florida

Pompano Beach, Florida (3 reports)

Saint Petersburg, Florida

Sarasota, Florida (2 reports)

Sebring, Florida

Titusville, Florida

Trenton, Florida

West Palm Beach, Florida (2 reports)

Winter Springs, Florida

Zephyrhills, Florida (2 reports)

Kihei, Hawaii

Baton Rouge, Louisiana

Covington, Louisiana

Gonzales, Louisiana

New Orleans, Louisiana

Elizabeth City, North Carolina

Okatie, South Carolina

Memphis, Tennessee

Austin, Texas

Conroe, Texas

Dickinson, Texas

Fort Worth, Texas

Grapeland, Texas

Liberty, Texas

Longview, Texas

San Antonio, Texas

Spring, Texas

show all

Gardeners' Notes:


On Mar 29, 2016, coriaceous from ROSLINDALE, MA wrote:

The Florida Exotic Pest Plant Council has listed this species as a Category ll invasive. It is capable of damaging and displacing native habitat.

There are many other plants that attract butterflies without harming Florida's environment.


On Jul 23, 2013, purplelady45 from Palm Beach Gardens, FL wrote:

Beautiful plant i have it in my pollinator garden in blue and red .


On May 11, 2013, Suzy_Bee from Spring, TX (Zone 9a) wrote:

Bought two one-gallon Porterweed plants from Arbor Gate in Tomball, Texas. They were selling it in the native plant section, and I've always assumed it was a native. Can't wait to try for some good butterfly shots when they find it.


On Nov 19, 2012, Daddysbug from Conroe, TX (Zone 9a) wrote:

First time growing Porterweed. The butterfies cover it to the extent that I can barely see the blooms. Mine is planted in full sun and is 7' tall. I will move it to a spot this fall where it will not shade out other sun-loving plants. So far, it has not been invasive (one year). I will tolerate invasive for the beauty of the plant and the butterflies.


On Sep 26, 2012, gardenwidow from Altamonte Springs, FL wrote:

Hi from Sunny Altamonte Springs FL: Porterweed, which I have always refered to by the name of butterfly tree.... I have come to be overloaded with in the purplish/blue variety. I love them and they love me! When my husband was alive we had one plant at all times. I am not sure if he dug up the babies all the time or they just never multilplied till I had the duty of gardening alone. I share them all the time with family, neighbors and friends. I just found some today in a clearance rack at Lowes in a red color. I love that shade and picked up a few of the plants to share.....My garden is loaded with butterflies, humming birds all the time. The plants grow so big I have to cut them down to less than 2 feet tall in August and they will regrow in the next month or two. They are hardy in... read more


On Sep 19, 2012, jfelker from Memphis, TN wrote:

This plant looks beautiful in a pot and blooms all year round in Memphis TN. It is in partial shade. I thought it had died once when it got extremely hot and dry and I didn't water it. It got brown and stopped flowering. But it bounced right back when I went back to watering occasionally during the heat wave and is better than before.


On Mar 2, 2011, anyoltime from Brandon, FL wrote:

as of last update02/2011 it doesn't appear that there has been a determination of "invasiveness" see link
then click on conclusion by common name then search
porter weed till you see stachytarpheta cayennensis next to it.
also one other florida invasive site lists only south florida,not central or north florida as areas where this plant is invasive.
one could assume that the colder winter temps keep it in check.....but ill wait for the investigators to do there job.
i currently grow it in full sun and partial shade locations with great success.


On May 24, 2010, angcentralfl from Homosassa, FL wrote:

This plant is an annual where I live, but very well worth planting each year if you are looking to attract butterflies-the most sought out plant in my butterfly garden. Starts off about 18 in. tall when i buy it, and ends up being a bush about 4ft. tall before it freezes, and so wide, it starts to kind of 'topple" over.


On Apr 24, 2010, dermoidhome from Baton Rouge, LA wrote:

Great hummingbird plant, but not winter hardy here in Baton Rouge (8B).


On Feb 6, 2008, Rainbowman18 from Weston, FL (Zone 10a) wrote:

"Hey, where did that come from?" was my thought when I saw blue Porterweed growing in between and higher than my trimmed snow queen hibiscus. After some thought and consideration, I remembered that the neighbor to the west of me had a stand of the plant in their yard about 100 feet from where mine were a' poppin'.

I was enamored with the purple-blue small flowers and the definite contrast to the variegated white and green leaves of the snow queen. Mine are the woody, tall variety, growing to about 6 feet or more.

As a matter of fact, they have dropped seed and saplings have emerged, which I then transplanted to a less obscure part of my garden. Two of the plants now have center stage near some gloxinia sylvatica (Bolivian Sunset) and variegated agaves in the... read more


On Jan 29, 2008, iae from Durban,
South Africa wrote:

This amazing plant grows very fast in gardens on the east coast of South Africa. It is perpetually in bloom and attracts large numbers of bumble bees, honey bees, butterflies and birds - outdoing even the pentas. It is best grown in clusters to avoid that leggy look and once established is a colourful addition to the garden requiring little maintenance. I have both pink and purple ones but have difficulty in telling the varieties of stachytarpheta apart since s. mutabilis, s. urticifolia and s.cayennensis are so similar.


On Dec 20, 2007, htop from San Antonio, TX (Zone 8b) wrote:

I have not grown this plant. Porterweed (Stachytarpheta urticifolia) which is a naturalized (introduced) plant in Florida, Hawaii and Puerto Rico. Having had great difficulty identifying a porterweed because some photos on the internet have been misidentified as well as the descriptions of some types of porterweed can be incorrect, I am adding a portion of an article entitled "Plant Profile: The So-Called Porterweeds". This information is written by Roger Hammer appeared on the Florida Native Plant Society webpage (Copyright 2003-2007 --- Revised July 14, 2006) - Reprinted from The Tillandsia (Miami-Dade Chapter), Jul.-Aug. 1994.

"Plants offered in many Florida nurseries and garden shops are either mislabeled or sold under names with no botanical standing. This adds to the ... read more


On Oct 25, 2007, MotherNature4 from Bartow, FL (Zone 9a) wrote:

I don't think any of you are listening to NativePlantFan9. He is absolutely correct. This plant is INVASIVE. We may think it is nice that it reseeds in our yards, but it reseeds EVERYWHERE.

Please, GO NATIVE with S. jamaicensis.


On Oct 29, 2006, donnacarl from Houston, TX wrote:

I stumbled across this plant in a Houston, Texas nursery about 4 years ago and had never seen it before, so I bought it. It was labeled "Porter Weed" with no other identification. I haven't found it offered here in any nursery since, and when I asked about the plant, I was told I would need a better name than Porter Weed to locate it.

This has got to be one of my all-time favorite plants. Though the flowers are small, they are constant, and the deep blue color is eye-catching. My plant is just off the patio where it is seen year round, and it's always beautiful and always covered with butterflies, some of which I've never seen before. They flock to the Porter Weed all day long and cling to the flowers and stalks with wings spread. I've taken some really neat pictures while ... read more


On Sep 10, 2006, t_florida from Gainesville, FL wrote:

This is by far the best performing plant in my garden! I always see it sorrounded by zebra long-tail butterflies during the Fall here in Florida. Seeds are easy to collect when the stems with flowers "die" off.


On Dec 23, 2005, budgielover from Pinellas Park, FL (Zone 9b) wrote:

I love this plant. I have the red, purple and salmon varieties. The red may indeed be a different species as it tends to be a lower mounding shrub unlike the other two that can get leggy. Still and all, they are all very nice plants and a great addition to a butterfly garden. I mulch the bottoms of mine and have never yet as volunteer seedlings. Sometimes I wish I did as it would have me from propagating from cuttings.


On Oct 25, 2005, Willygator from Gulf Breeze, FL wrote:

Grows well in Gulf Breeze, Florida (panhandle-Pensacola zone 8B). Planted in 2004 in the shade of a medium Dogwood tree (full morning sun, filtered early afternoon sun and full late afternoon shade). In 2005 it took off and has bloomed all year but most prolifically in Spring and Fall. Currently (Oct 05) it is 4.5 feet tall and 4 feet wide. Soil is very sandy with a slight topsoil layer. Butterflies love it.


On Sep 27, 2005, NativePlantFan9 from Boca Raton, FL (Zone 10a) wrote:

This exotic species is much more commonly sold in central and southern Florida nurseries than the native S. jamaicensis; however, it is often erronously (and mistakenly) sold as the latter native species. Here are the differences between the two species:

S. urticifolia:
-Large to medium, spreading shrub
-Exotic (not native) to Florida
-More commonly sold than the native S. jamaicensis
-Has thinner, more sharply cut (divided) leaves than the native species, hence the common name 'Nettle-leaf Velvetberry'
-Can get lanky and unattractive after a while, unlike the native species; higher maintenance
-Has smaller, darker violet/purple flowers than the native species
-Has longer, thinner flower stalks than the native species
<... read more


On Jun 4, 2005, michaeladenner from Deland, FL wrote:

A woody perennial here in Central Florida (zone 9a) -- mine is 4'X2.5', after a heavy prunning in February. Grows in partial sun (morning sun, 3 hours or so) and full sun. Low water needs, and I've never fertilized mine. Leaves are pinnate, serrated, pleasant dark green. Year-round flowers, although upper part of plant browns in cold weather. Blooms are tiny on sometimes very long (18") "rat tail" panicles. Self-sows fairly prolifically, but the seedlings are easy to identify, dig up, and transplant. Also very easy to propagate from cuttings. I can't say it's a stunning flower, but hummers and butterflies and bees all love it, and it's very low maintenance.


On Feb 27, 2005, mcgrawts from Miami, FL wrote:

Definitely attracts butterflies. My monarch caterpillars like to form their pupas under the leaves. Very, very pretty plant.


On Dec 6, 2004, CostaRica from Guayabo de Bagaces, Guanacaste,
Costa Rica (Zone 10b) wrote:

One of the most prolific flowering shrubs here in Costa Rica
How anyone could think it 'weedy looking' I would disagree with! Both butterflies and hummingbirds abound! Very often grown a a hedge.


On Nov 7, 2004, IslandJim from Keizer, OR (Zone 8b) wrote:

This is one of premier butterfly plants in southwest Florida. It is kind of weedy looking, however, so you may not want it anywhere except in a butterfly garden.


On Nov 1, 2004, jameso from Longview, TX wrote:

I have all kinds of salvia's sages and other hummingbird plants but the porterweed seems to be the most popular with hummingbirds in my East Texas garden.


On Aug 4, 2002, bleu wrote:

The dark blue porterweed (Stachytarpheta cayennensis) is a great addition to any butterfly plant. This plant can seed a little too freely so give it lots of elbow room.

There is a pink variety of this plant which can grow rapidly to 12' and puts out quite a show. The soft wood can get wind whipped and break off in storms very easily but it quickly grows back again.