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Purslane Identification

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Habitat and Distribution

Purslane (Portulaca oleracea) is a common plant of open, sunny areas, such as gardens, yards, and roadsides. It’s not picky about its habitat— you can find it growing in gravel, sidewalk cracks, disturbed soil, and other “waste places.” It is commonly found across the lower 48 states, Hawaii, and all the southern Canadian provinces.

The succulent stem of purslane (Portulaca oleracea).

Identification

One of the keys to identifying purslane is its fleshiness. The stems are thick and succulent, reddish in color, and spread into dense mats up to 20 inches across. The leaves are succulent as well, and grow in an alternate fashion on the stem, though they may be crowded enough to appear opposite or whorled. Leaves are spatula-shaped, with the broadest point above the middle, up to 1/2 inch wide, and typically 3/8 to 2/3 inch long. They are smooth, green in color, and may have a reddish tinge around the edges.

Flowers are small and and yellow, 1/8 to 1/4 inch across, with 4 to 6 notched petals. Two or four sepals grow behind the flower. The flowers grow singly or in small clusters.

Seeds grow inside small oval to urn-shaped pods, up to 1/3 inch long. These pods have a seam around the middle which eventually splits open, revealing many tiny black seeds.

This is NOT a Dandelion.

Gardeners cursing as they yank out yellow blooms from the ground might be misplacing their anger. Not everything that looks like a dandelion is one.

This is not a dandelion. To tell this catsear from its better-known relative you need to look under its petals. (Josh Cassidy/KQED)

Dandelions have many doppelgangers, among them the most successful plant you’ve never heard of: catsears. Their claim to fame is that they were recently a clue in the New York Times crossword puzzle (“Dandelion look-alike”), but the plant is so prolific — it has spread from its native Morocco all around the world — that it doesn’t really need any press.

Chances are you’ll run across both dandelions and catsears in your backyard or at the park this fall, especially if they’re getting watered. Catsears also proliferate in pastures, where cows keep the grasses that compete with them at bay.

A lesser goldfinch munches on catsear seeds in Berkeley.

Bees and butterflies love the nectar and pollen provided by dandelions and catsears, and little songbirds like lesser goldfinches feed on their seeds. But it’s hard to convince some gardeners of their virtues.

“Most people who have a nice turf want only grasses,” said Joe DiTomaso, a weed researcher who retired from UC Davis.

Catsears in bloom in a backyard in Berkeley in June. (Josh Cassidy/KQED)

Frustratingly for lawn lovers, efforts to keep the turf looking good sometimes help dandelions and catsears. Their leaves grow close to the ground, so when the lawnmower chops down any blades of grass towering over them, they can more easily soak up the rays they need to grow.

Whether you’re a friend or a foe, telling dandelions and catsears apart could be useful — if only to know thine enemy — and a fun way to ponder what makes these yellow blooms so successful.

If you’re looking down at them, you’ll miss their differences. You need to get on your knees and take a close look.

Below their petals you’ll see green structures that hold the bloom. They’re called phyllaries. In catsears, they all point up. In dandelions, some phyllaries curl down.

Catsear or dandelion? The green structures called phyllaries that hug the bloom all point up in catsears. (Josh Cassidy/KQED) Dandelions’ curly phyllaries are one way to tell them apart from catsears. (Josh Cassidy/KQED)

Dandelion and catsear leaves have a similar shape, with toothed edges that give dandelions their name — an adaptation from the French dent-de-lion, or lion’s tooth. The leaves of the common catsear are more lobed than pointy and they’re furry, while dandelions’ are smooth. Both leaves are edible, prepared in salads or sauteed.

Catsears’ leaves are furry (left); dandelions’ are smooth. Both are edible. (Josh Cassidy/KQED)

“If you eat an old dandelion leaf, it’s going to be extremely bitter,” said Austin Lynn, who studied the plants for his recently completed doctoral studies at the University of Missouri. “But if you eat a younger one, it’s much more pleasant.”

In a taste test he carried out, Lynn said dandelion leaves were described as similar to romaine lettuce or arugula.

Both dandelion and catsear blooms transform into fluffy globes called “clocks,” full of seeds. The dandelion’s clock is like a head of wispy gray hairs that just came from the salon, while the catsear’s featherlike globe looks like a dandelion that let its mane dry in the wind.

Both catsears and dandelions create globes full of seeds, called “clocks.” Catsears’ clocks (left) look like a messier version of dandelions’. (Josh Cassidy/KQED) Catsear (left) and dandelion dried, ribbed fruits waiting to be carried away by the wind. A tiny seed is hiding inside each fruit. (Josh Cassidy/KQED)

One other way to tell them apart is that each stem of catsears branches into multiple blooms, while dandelions have only one bloom per stem.

But for all their differences, dandelions and catsears are closely related and pollinator favorites. That’s because of a tiny secret up in their petals: What we think of as a dandelion or a catsear flower is actually a cluster of dozens of tiny flowers called ray florets. Each floret makes its own pollen and nectar, which attract a host of different bees, butterflies and other insects.

Catsears serve all customers.

“They have generalists as their pollinators,” said DiTomaso. “There are not specific insects that are required to pollinate them.”

An umber skipper butterfly sips nectar from a catsear in Berkeley. (Josh Cassidy/KQED)

The dandelions in your backyard, called common dandelions and hailing from Europe, don’t even need pollinators to reproduce — they just clone themselves.

“If one dandelion makes it to a new habitat, it can colonize that new habitat with just one individual,” said Lynn. “These dandelions don’t need to have a mate; that’s one of the big advantages.”

Make a wish! Dandelion pappi fly away. (Josh Cassidy/KQED)

Wind disperses both dandelions’ and catsears’ seeds, another reason for their success. Each floret produces a fruit with a tiny seed inside, and each fruit floats away hanging from an umbrella-shaped structure called a pappus. These tiny pappi (PAP-eye) are what children blow on after making a wish.

“They’re very good at catching wind to detach,” said Naomi Nakayama, a researcher at Imperial College London who has studied dandelion flight.

A dandelion pappus catches the wind and carries away a dry, ribbed fruit. A tiny seed is nestled inside the fruit. (Josh Cassidy/KQED)

The pappus acts very much like an open umbrella that lifts easily on the wind, even though it’s mainly empty space. Because of its small size, a trick of physics makes it so that the air in between the bristles of the pappi behaves like a solid — sort of like a viscous honey.

“They have an invisible wall they create,” said Nakayama. This helps pappi lift off when the wind hits them. The wall effect also helps the pappus stay adrift. Some air sifts through the bristles and a lot of air swirls around and above the pappus, forming a whirlwind that sucks the pappus up and keeps it afloat.

The vast majority of pappi don’t carry their seed very far — just enough for it to germinate in your backyard. How far they can travel is an open question, Nakayama said, since attaching a GPS onto them would impede their flight.

Most dandelion fruit will likely fall to the ground nearby. (Josh Cassidy/KQED)

“A lot of people feel comfortable saying they can travel a couple of miles,” she said.

TexasInvasives.org – Home

Alternanthera philoxeroides

Alligatorweed

Synonym(s): Achyranthes philoxeroides
Family: Amaranthaceae (Amaranth Family)
Duration and Habit: Perennial Herb

Additional Images

Photographer: Chris Evans
Source: The University of Georgia, Bugwood.org

Description

Alligatorweed is an emergent or rooted floating perennial invasive that often forms very dense stands along the shore. The stems growing in the water are hollow and can be single or branched. Its leaves are opposite and non-succulent, elliptical or lance-shaped, up to 3/4 inch wide and 5 inches long with a prominent midrib. Soft, whitish hairs are found in the leaf axis. The white flowers occur in short, headlike spikes. The flowers resemble those of white clover. A single seed develops within the fruit.

Native Lookalikes: Water willow (Justicia americana) is the native species most likely to be confused with alligatorweed. Its flower is more orchid-like (bilaterally symmetric) and purple-and-white with purple bee-guides, while alligatorweed’s flower is more radially symmetric and white with papery sepals that look like petals. Alligatorweed’s inflorescence is reminiscent of a clover’s. Water willow grows taller than alligatorweed, about 1.5 to 3 ft tall compared to about 1.5 ft. While the leaves look similar, alligatorweed’s can be up to 2 inches shorter than the minimum 3-inch length of water willow leaves.

Water smartweed ( Polygonum amphibium ) is another aquatic perennial that might be confused with alligatorweed. It is distinguished by having alternate leaves and pink flowers.

Images and further information on Native Lookalikes

Ecological Threat: Alligatorweed forms thick mats that crowd out native aquatic vegetation, retard water flow, lower dissolved oxygen levels, and increase sedimentation. Flooding may result from impeded drainage. Can restrict water flow for irrigation. Inhibits fishing, and other water recreation.

Biology & Spread: Reproduces vegetatively from stolons. Each node or fragment with a node is capable of producing a new plant. Plants are highly competitive and have rapid growth rates. Plants rarely grow in water deeper than 2 m. Seeds rarely develop, and those that do are seldom viable.

Plants grow best under high-nutrient (eutrophic) conditions. Mechanical removal without careful removal of all plant parts can facilitate spread. Stolon can regenerate from burial to 30 cm (

History: Alligatorweed is native to South America and was first introduced into the United States around 1900.

U.S. Habitat: Shallow water or wet soils, ditches, marshes, edges of ponds and slow-moving watercourses. Tolerates saline conditions (to 10% salt by volume). Requires a warm summer growing season. Tolerates cold winters, but cannot survive prolonged freezing temperatures.

Distribution

U.S. Nativity: Introduced to U.S.

Native Origin: So. Amer. (Germplasm Resources Information Network); NatureServe Explorer

U.S. Present: AL, AR, CA, FL, GA, KY, LA, MS, NC, PR, SC, TN, TX, VA

Distribution in Texas:

Mapping

Invaders of Texas Observations

Native Alternatives

Management

Prevention: A. philoxeroides generally will not establish in water deeper than 2 meters. Proper pond construction can minimize shallow edges and prevent establishment. Likewise, establishment of competitive grasses or other native species on the banks of ponds and irrigation ditches will reduce soil erosion and prevent alligatorweed from gaining a terrestrial foothold.

Mechanical: Since this plant will regenerate from rootstocks and fragmented stems, removal of the dense floating mats will only provide temporary control. Care must be taken to prevent transport of detached stems downwater, where re-establishment can rapidly occur. Tillage of terrestrial plants may sever roots and shoots, which may increase the spread of the plant.

Biological: There have been three South American insect species released between 1964 and 1971 to control A. philoxeroides, with varying degrees of success. The alligatorweed flea beetle Agasicles hygrophilia may cause considerable damage to aquatic mats of A. philoxeroides. It feeds on the leaves and bores into stems, where it pupates before adulthood. Unfortunately, it will neither feed upon nor reproduce in terrestrial plants. Considerable success has been shown in the southeastern United Sates. However, repeated attempts at establishment in California during 1967-1969 met with little success and no further colonizations were attempted. The alligatorweed stem borer Vogtia malloi is a small moth which lays eggs on the apical leaves. The larvae bore into the stem tips and move down the stems. Infested stems rapidly wilt and droop. This damage can be easily distinguished from the flea beetle’s characteristic leaf stripping of plants. The insects were initially released in Florida, Georgia, the Carolinas and Alabama from 1971 to 1973, and have since been reported in Arkansas, Louisianna, Mississippi, and Texas. A thrips species, Amynothrips andersoni, attacks and deforms apical leaves of both aquatic and terrestrial plants. Damage, however is relatively minor and scattered. Attempts to establish this species from 1967 to 1971 in Albany, California were unsuccessful. Most adults are wingless and dispersal is somewhat limited.

Chemical: The following herbicide treatments have demonstrated considerable success, although retreatment is necessary.

1) 2,4-D at 8 lb/A mixed with 8 oz of detergent applied in 50 gallons of water per surface acre.

2) Glyphosate (Rodeo) at 6 pints per acre + X-77 non ionic surfactant at 3 pints per acre applied in 50 gallons of water per surface acre.

3) Dicamba (Banvel 720) at 1 gallon + Rodeo at 1 quart + X-77 at 1 pint applied in 50 gallons of water over plants.

Read and follow all label directions before applying any herbicide to water. Misuse may cause extensive damage to other nontarget plants, both native and agricultural.

USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS. MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.

Text References

Buckingham, G. R. 1996 Biological control of Alligatorweed, Alternanthera philoxeroides, the world’s first aquatic weed success story. Castanea. 61:232-243.

Clark, W. R. 1973. Alligatorweed. Annu.Proc.Calif.Weed Conf. 25: 49-50.

Coulson, Jack R. 1977. Biological control of alligatorweed, 1959-72. A Review and Evaluation. USDA Technical Bulletin No. 1547.

Goeden, R. D. and Ricker, D. W. 1971 Imported alligatorweed insect enemies precluded from establishment in California. J.Econ.Entomol. 64:329-330.

Hill, W. G. and Donley, R. G. 1973. Alligatorweed report: Los Angeles County. Annu.Proc.Calif.Weed Conf. 25: 43-48.

Julien, M. H. and Broadbent, J. E. 1980 The biology of Australian weeds. 3. Alternanthera philoxeroides (Mart.) Griseb. J.Aust.Inst.Agric.Sci. 46:150-155.

Kay, S. H. and Haller, W. T. 1982 Evidence for the existence for distinct alligatorweed biotypes. J.Aquatic Plant Manage. 20:41-

Rees, N. E., Quimby, Jr. P. C., Piper, G. L., Coombs, E. M., Turner, C. E., Spencer, N. R., and Knutson, L. V. 1996. Biological Control of Weeds in the West. Bozeman, MT: Western Society of Weed Science.

Sandberg, C. L. and Burkhalter, A. P. 1983. Alligatorweed control with glyphosate Alternanthera philoxeroides, in aquatic environments. Proc.South.Weed Sci.Soc. 36: 336-339.

Tucker, T. A., Langeland, K. A., and Corbin, F. T. 1994 Absorption and translocation of 14C-imazapyr and 14C-glyphosate in alligatorweed Alternanthera philoxeroides. Weed technol. 8:32-36.

Weldon, L. W. and Blackburn, R. D. 1969 Herbicidal treatment effect on carbohydrate levels of alligatorweed. Weed Sci. 17:66-69.

Online Resources

Encycloweedia, California Department of Food and Agriculture