Flaveria linearis – Yellow Top

A beautifully grown flowering plant of Flaveria linearis photographed in the native plant garden of Ryan Leavengood, a member of the Palm Beach County Chapter of the Florida Native Plant Society.

Flaveria linearis is a common, easily grown perennial found in open, sunny areas in pine flatwoods and coastal situations from Jackson County in the Panhandle, south to the Monroe County keys. It is easily grown from seeds as well as vegetatively by division or cuttings, the latter readily rooting in a glass of water or a pot of moist soil. Its cultivation is undemanding and requires nothing more than moist, but well-drained soil, and a half-day or more of full sun. It tends to be short-lived in cultivation, especially if grown in very rich or heavily fertilized soil.

Although it bears small flower heads, Flaveria linearis puts on an attractive show due to the sheer number and brilliant golden-yellow color of the flower heads. Plants in flower are irresistable to a wide variety of insects including flower beetles, native bees, and butterflies. After flowering, the plants get a somewhat unkempt appearance due to the old dried flower heads but a little judicious pruning soon leads to a burst of fresh, bright green, new growth.

Flaveria linearis may be grown in flower beds, cottage gardens, bee or butterfly gardens, wildflower gardens, or along the sunny edges of shrub borders or tree plantings. Because it can tolerate much adversity, it may also be grown in tough urban situations as well as sites where construction has disturbed the soil and there is much rubble present. It naturally occurs in coastal sites and is thus also recommended for coastal gardens. The bright yellow flower heads and its long stems make Flaveria linearis a good plant for cut flowers. And, while it has no medicinal or herbal uses that I know of, its growth habit and appearance permit its use in herb gardens, where its bright green leaves will constrast nicely with silvery-leaved herbs. Its wide natural range from Florida's Panhandle to the Floria Keys indicates that it is an adaptable plant capable of being grown throughout the entire State of Florida. Yet, in spite of its vigorous, carefree nature, it is well-behaved in most gardens and is rarely, if at all, ever weedy due to aggressive self-seeding. Its ease of cultivation, showy golden flower heads, and benefits to native insect wildlife, highly recommend Flaveria linearis for any garden that can accommodate its needs, including those of novice gardeners or gardeners with little experience growing perennials, wildflowers, or native plants.

Image and text © 2013 Rufino Osorio

Spanish Daisy and Company

A Spanish daisy, Helenium amarum, made itself at home in my carport. It is a perky and pretty yellow annual daisy native to Florida. It is joined by two additional native annuals: slender three-seeded mercury, Acalypha gracilens, and partridge pea, Chamaecrista fasciculata. Rounding out this little micro-biome are two native perennial grasses (Paspalum species). One of the grasses is visible on the left side of the Spanish daisy and just a hint of the leaves of the second grass is visible at the extreme left of the photograph.

Image and text © 2013 Rufino Osorio

Symphyotrichum georgianum – Georgia Aster

This exceptionally deep violet-purple form of the Georgia aster is the cultivar 'N3 Purple Haze'.

Georgia aster (Symphyotrichum georgianum) is a colonial, rhizomatous perennial with flowering stems 1.5–3 feet (50–100 centimeters) tall. It is listed by the USDA as occurring in Alabama, Florida, Georgia, Louisiana, North Carolina, and South Carolina. In Florida, it is a rare plant that is listed as occurring only in Leon County by the Atlas of Florida Vascular Plants.

On March 17, 2006, I acquired a small plant of the deep violet-purple cultivar 'N3 Purple Haze' and planted it in a sunny site in well-drained sandy soil. It quickly spread by way of underground rhizomes to form a patch that covered about 1.5 square feet (0.4572 square meters). To my surprise, the colony has never grown beyond those 1.5 square feet even though there are no obstacles or larger plants preventing its spread. Thus far, it has not been attacked by the aphids, caterpillars, mealy bugs, scales, nematodes, grubs, or viruses that prove so troublesome in south Florida.

New stems of Georgia aster emerge in early spring.

Georgia aster flowers abundantly and spectacularly but it is among the last of the wildflowers to bloom in my garden and begins to flower at the end of October or the beginning of November. The only other wildflower in my garden that blooms later are my clones of Symphyotrichum concolor (eastern silver aster) from Miami-Dade County, which do not flower until the end of November or even December. After flowering, the stems dry up and I remove them. Unlike some asters, the stems of Georgia aster tend to recline, or even lie on the ground, with age. Gardeners who desire a more formal appearance can trim back the plant in mid-summer, a treatment that results in shorter, more erect flowering stems.

Like most rhizomatous perennials, Georgia aster is easily propagated by splitting off and potting up new growths in the spring. My single plant has never set viable seed, which indicates that Georgia aster is self-sterile. This year I've acquired a second clone and I'm hoping to obtain viable seed next year. The new clone has flowers of the typical color for the species, deep blue rather than purple-violet, and I'm hoping that, by crossing the two, I will get progeny whose flowers will come in a range of blue, violet, and purple colors. Craig Huegel has images of plants with the typical deep blue flowers at his blog, Native Florida Wildflowers.

Images and text © 2012 Rufino Osorio

Amelia's Smarty Plants

Jatropha integerrima is a drought tolerant shrub from Cuba in the euphorbia family (Euphorbiaceae). It is very common in south Florida gardens and is often recommended for butterfly gardens.

Amelia's Smarty Plants is a full service neighborhood garden center located at 1515 North Dixie Highway in Lake Worth, Florida (phone number: (561) 540-6330). Plants in stock are very diverse and include a wide variety of subtropical and tropical ornamental plants as well as flowering annuals, herbs, and a diverse selection of Floria native plants. Below are a few photographs that I took on a recent visit.

Justicia betonica, the white shrimp plant, is native to Africa and has unassuming flowers peeking out from white, green-veined bracts; however, the flowers apparently produce ample nectar since they are avidly visited by honeybees. Like many shrimp plants in the genus Justicia, it has plain green leaves and is vegetatively nondescript.

Nerium oleander 'Variegata' is a variegated oleander with brilliant chartreuse leaves that gradually develop varying amounts of green. The flowers are blousy pink things that I do not find particularly attractive. Oleander is now cultivated throughout the subtropics and tropics of the world but was originally native to western Asia and the Mediterranean region of Europe and northern Africa. Formerly regarded as non-invasive in the United States, it is now listed as invasive in Arizona and it is escaping to floodplains and riparian zones in California.

The pink trumpet vine, also known as Zimbabwe creeper (Podranea ricasoliana), is an African vine in the bignonia family (Bignoniaceae). It has escaped cultivation in a few counties in Florida. Such occurrences should be carefully monitored to see if, like many tropical vines, it has invasive tendencies.

This is a hybrid Tecoma and the flower color and flower form leave no doubt that it is in the same family (the Bignoniaceae) as the native trumpet creeper (Campsis radicans). And like the native trumpet creeper, it is attractive to hummingbirds. The genus Tecoma is native to both the New World tropics as well as to Africa.

Chrysanthemum ×morifolium, the garden chrysanthemum, was domesticated in China where it was originally used as a culinary herb and tea plant. It generally does not survive south Florida's hot and humid summers; however, many garden centers carry them as short-lived decorative flowering plants to brighten the autumn garden. The plant pictured here has pom-pom flowers, one of 13 classes into which chrysanthemum flowers are categorized.

This showy chrysanthemum with brilliant autumnal colors has semi-double flowers, another of the 13 classes into which chrysanthemum flowers are categorized.

Images and text © 2012 Rufino Osorio

Zinnias etc.

Cosmos sulphureus, a short-lived annual native to the American tropics, is attractive to many insects.

UPDATE: The United States Department of Agriculture Plants Database lists the scientific name of the common garden zinnia as Zinnia violacea; however, the Atlas of Florida Vascular Plants uses the name Zinnia elegans and lists Zinnia violacea as a nomen rejiciendum (a rejected name) under the rules of the International Code of Nomenclature for Algae, Fungi, and Plants. As a result, the name Zinnia elegans is used in this blog post.

I visited the garden of Robert Hopper today and found that his cottage garden annuals were in full bloom. Further north, these annuals would be planted in the spring to flower in the summer. Here in south Florida, they are planted in the autumn to flower throughout the winter.

Some of the plants in flower included Cosmos bipinnatus, Cosmos sulphureus, Portulaca grandiflora, Salvia farinacea, Zinnia angustifolia, and Zinnia elegans. Except for Salvia farinacea, which is a perennial native to Texas and New Mexico, these plants are all annuals native to Central or South America. To date, none have exhibited invasive tendencies in the United States and all have showy flowers that are attractive to numerous native pollinating insects as well as to honeybees. The plants of Zinnia elegans apparently came from open-pollinated seeds Burpee's Cut & Come Again Mix and a wide variety of colors and forms, including singles, semi-doubles, and doubles, were present in the garden. Fully double zinnias have little or no wildlife value but zinnias with single and semi-double flowers are irresistible to honeybees, native bees, hover flies, skippers, butterflies, hawk moths, various flower-visiting wasps, and hummingbirds.

Zinnia elegans, the common garden zinnia, tends to be short-lived in south Florida and is subject to diseases and pests that disfigure the leaves such as viruses, downy mildew, and leaf miners. It was originally native to Mexico but can now be found in gardens nearly throughout the world. If allowed to go to seed, it can persist in garden settings from self-sown seedlings but it eventually reverts to its wild form and plants with double, pom-pom-like flowers are replaced by plants with single or semi-double flowers. It also tends to escape from cultivation, especially to roadsides and other areas kept free from competing vegetation by natural disturbances or human activity; however, it generally does not persist for long.

Below are images of a few of the plants in Rob's garden as well as a rather extensive gallery of some of the many variations of Zinnia elegans that sprung up in his garden.

Angelonia angusifolia soon dies in my garden but this attractive dark purple form has proven to be long-lived in Rob's garden. Originally native to Mexico and Guatemala, it is now widespread in the tropics as an escape from cultivation.

Landoltia punctata has formed a solid cover on the surface of a small aquatic garden in Rob's yard. It is frequently misidentified as a native duckweed; however, no North American records are known prior to its occurrence in 1930 in a goldfish pond in Kansas City, Missouri, and it is now known to be native to southeast Asia and Australia.

Zinnia angustifolia is a small annual that produces numerous brilliant white, yellow, or orange daisies. It does not last long in the garden since it tends to quickly flower and seed itself to death. Native to Mexico, it has been bred with Zinnia elegans to produce a hybrid zinnia that has the disease resistance and abundant flowers of the former with the large flower size and range of colors of the latter.

All subsequent images are of the various forms of Zinnia elegans that sprung up in Rob's garden.

Zinnia elegans with flowers of an unusual burnt orange color. In the upper right, one can see the attractive flower buds typically found in garden zinnias. These are globose and have green bracts with black-rimmed margins.

Plants of Zinnia elegans with single flowers, such as this one, have the most wildlife value since the yellow disc florets provide plenty of pollen and nectar.

A plant of Zinnia elegans with semi-double flowers.

Plants of Zinnia elegans with fully double flowers, such as this one, lack the pollen- and nectar-bearing disk florets and have little value to insect wildlife.

The discoloration of the leaf in the upper right hand corner of the photograph is the result of leaf miners.

The flower heads in this photograph and the following two photographs are displaying symptoms caused by the Bidens mottle virus, which causes deformities of the leaves as well as color breaks in the flowers.

Color breaks, such as those shown in this photograph, are a symptom of the Bidens mottle virus. The virus is spread by aphids and is hard to avoid since Bidens alba, a common and abundant weed of south Florida, serves as a reservoir by which the virus can readily infect garden plants.

The effects of Bidens mottle virus are sometimes dramatic and colorful as in the above example; however, if such plants are not destroyed they will act as a reservoir for the virus and allow the virus to spread to other plants.

A honey bee, Apis mellifera, on Zinnia elegans. The foliage in the background, as well as in the flower buds in the lower left hand corner, belong to Cosmos sulphureus.

The spiny branches visible in the photograph belong to Acacia pinetorum, a small, shrubby, native acacia that becomes a mass of fragrant, yellow, globose flower heads in the spring.

Images and text © 2012 Rufino Osorio

Symphyotrichum oblongifolium 'Raydon's Favorite'

Symphyotrichum oblongifolium 'Raydon's Favorite' is a big bang bloomer that covers itself in flowers in the autumn.

Every year since 1996, Symphyotrichum oblongifolium 'Raydon's Favorite' reliably flowers in my garden towards the end of the year in late October and November. The common name is "aromatic aster" and it is based not on the fragrance of the flowers but rather on the aromatic glandular hairs of the bracts below the flowers.

The flowers are a clear amethyst-lavender color that never fails to attract the attention of butterflies and native bees.

So far, after 16 years of cultivation in south Florida, it has weathered droughts, intense heat and humidity, tropical storms, and hurricanes. And it has done so without ever having been afflicted by a single pest—not even aphids. What is puzzling is that it is a species of the eastern and central United States from where it extends west to Montana, Wyoming, Colorado, and New Mexico. The closest that its natural range gets to Florida is North Carolina with reports from Alabama and Mississippi. Yet, it thrives in subtropical south Florida. I have tried growing other cultivars as well as wild forms of Symphyotrichum oblongifolium but all languish and die out after a year or two. But 'Raydon's Favorite' lives on to flower every year and no doubt becomes the favorite of every gardener who makes room for it in his or her yard.

Its cultivation is essentially effortless so long as it is provided with well drained soil and plenty of sunshine, although it appreciates a little water during extended droughts. It spreads vigorously and rapidly from underground suckers and propagation is easily effected by digging up and potting up the young suckers in the spring. Viable seed has never been set in my garden and, like many ecologically conservative perennial members of the daisy family, aromatic aster appears to be self-sterile.

Images and text © 2012 Rufino Osorio

Gaillardia pulchella – Firewheel

Gaillardia pulchella has several common names, including "indian blanket" and "firewheel."

Gaillardia pulchella is an easily grown annual commonly cultivated for its showy flowers. The flowers are exceptionally attractive to native bees as well as to a wide variety of both large and small butterflies. Although commonly regarded as native to Florida, the genus is centered in the great plains of the United States. Also, Florida plants exhibit wide variation in the size, form, and color of the ray florets (the so-called petals of a daisy), and this bolsters the possibility that perhaps some populations in Florida are derived from plants that escaped cultivation. This particularly showy form was photographed on a deeply overcast day at the Native Choice Nursery in Boynton Beach on Saturday, May 26, 2012.

Image and text © 2012 Rufino Osorio

Tithonia rotundifolia

Tithonia rotundifolia (Miller) S.F. Blake is an annual native to Mexico and Central America. Depending on the plant's genetics and growing conditions, it grows 3–6 feet tall. It is grown for its large, brilliant orange-red daisies, these being used as cut flowers or as a source of nectar in butterfly gardens. The plant is a serious invasive pest plant in some countries but it is not regarded as invasive in the United States, where it has sparingly escaped cultivation in Florida and Louisiana.

In my garden, plants of Tithonia rotundifolia were severely attacked by various insect pests and a plant virus almost as soon as they germinated and the severely weakened plants barely survived long enough for me to obtain the photograph above before promptly dying without setting seeds. In view of this plant's invasive tendencies in various tropical and subtropical regions, I did not consider its early demise in my garden unfortunate.

© 2010 Rufino Osorio.

Stokesia laevis – Stokes-Aster

Stokesia laevis (J. Hill) Greene is a perennial wildflower in the daisy family native to Alabama, Florida, Georgia, Louisiana, Mississippi, and South Carolina. It grows 1–2 feet tall and is distinctive for its large lavender-blue daisies which are borne in June–September. In nature it occurs in woodland openings, bogs, and wet flatwoods and savannas; however, it readily adapts to garden conditions in light shade to full sun in sites with rich, moist soil. Plants slowly form rather large clumps and it is easily propagated by division of the clumps. It may also be propagated from root cuttings and from seeds, which do not require any special pretreatments for germination. There are reports that seeds of stokes-aster may germinate irregularly over a long period of time (Gettys & Werner 2001); however, in one experiment, 78% of 985 seeds germinated within 42 days (ibid).

References:

• Gettys, L.A. and D.J. Werner. 2001. Stratification unnecessary for germination of seeds of stokes aster [Stokesia laevis (J. Hill) Greene]. Proceedings of the Florida State Horticultural Society 114:250–251. PDF

 

© 2010 Rufino Osorio.

Youngia japonica

Warning: Youngia japonica is an extremely pernicious non-native weed. It is included here only as an aid to identification and not to promote its cultivation in any way whatsoever.

Youngia is an Asian genus of about 30 species of annuals and biennials (or rarely perennials) in the daisy family. One species, Youngia japonica, is now a pantropical weed established throughout the warmer parts of Africa, Europe, Asia, Australia, Pacific Islands, and North and South America (Spurr 2006). Youngia japonica has been reported in the United States from every Gulf state as well as Arkansas, the District of Columbia, Hawaii, Kentucky, Maryland, North Carolina, Pennsylvania, South Carolina, Tennessee, and Virginia. Its presence as far north as Pennsylvania is perhaps indicative of significant cold tolerance and it may well become a truly cosmopolitan weed.

Youngia japonica forms a basal rosette of lobed leaves somewhat reminiscent of dandelions but it differs by its branched inflorescence, which bears one or two leaves and carries several to numerous small flower heads resembling tiny dandelions. The fruit is a one-seeded cypsela crowned by a tuft of stiff hairs that aid in dispersal by the wind. It is a remarkably adaptable plant and can grow in any moist site in full shade to full sun. It is usually not found in dry areas but it will tolerate considerably dry soil if situated in a shady spot.

Youngia japonica grows especially well in the pots of ornamental potted plants, both in gardens and commercial plant nurseries, and a single plant can quickly multiply into thousands, infesting every pot throughout an entire nursery. When such potted plants are shipped elsewhere, Youngia japonica is also inadvertently spread to new locations. For example, the first time I saw this species was in a specialty nursery in Chicago, where potted plants had been shipped in from Florida. All it would take is for the nursery owners to place the pots outdoors for the summer and it is likely that yet another non-native weed would soon be established in Chicago.

Once it builds up to a large population, Youngia japonica is extremely difficult to eradicate because even depauperate plants only an inch tall can flower and set seed, and such tiny plants are easily overlooked while weeding. In addition to being a nursery and garden weed, Youngia japonica is a common and tenacious lawn weed.

USDA Distribution Map

References:

• Spurr, P.L. 2006. Youngia. pp. 255–256. In Flora of North America Editorial Committee (eds.) Flora of North America: Volume 19. New York and Oxford: Oxford University Press. Internet
  
• USDA, NRCS. 2010. Youngia japonica. The PLANTS Database. Baton Rouge: National Plant Data Center. Internet

© 2010 Rufino Osorio (exclusive of the USDA map).

Silybum marianum – Blessed Milk Thistle

Warning: Silybum marianum has been listed as an invasive pest plant or noxious weed. It is included here only as an aid to identification and not to promote its cultivation in any way whatsoever.

Flowering plant in coastal California sage scrub. © 2010 Joseph Libertucci. Used by permission.

Silybum marianum is a biennial or winter annual originally native to the Mediterranean regions of Europe, western Asia (Israel and Turkey), and northern Africa (Egypt). It is now widely established outside of cultivation as a weed in tropical and southern Africa, northern Europe, the British Isles, Australia and New Zealand, and North and South America. It is readily identified by the spiny leaves that are conspicuously variegated, as well as by the flower heads, which are subtended by bracts whose tips expand into a leafy, spine-tipped appendage.

Foliage of young plant. © by Valérie75 2006. Used under a Creative Commons license.

Milk thistle seed extract (silymarin) has shown promise in the treatment of liver diseases, cancer, hepatitis C, HIV, diabetes, and high cholesterol, as well as protective effects against liver damage by poisonous mushrooms; however, there have been few high-quality randomized clinical trials to conclusively prove the therapeutic effects of milk thistle (see, for example, Tamayo & Diamond 2007).

Seedling. © by Beentree 2008. Used under a Creative Commons license.

Silybum marianum was touted as an ornamental garden plant in the 1980s and seeds were widely available from mailorder garden catalogs; however, its popularity has waned as gardeners realized that it dies after flowering and they must then deal with a large mass of dry and wickedly spiny foliage. It is still widely sold as an herb garden or medicinal plant but the therapeutic properties are contained in seed extracts and such extracts are easier to purchase ready-made than to make at home from seeds harvested in the garden. In several states, Silybum marianum is an invasive pest plant or a declared noxious weed. Thus, in view of its weedy nature as well as its toxicity to livestock, its cultivation should not be encouraged.

USDA Distribution Map

 

References:

• Tamayo, C. and S. Diamond. 2007. Review of clinical trials evaluating safety and efficacy of milk thistle (Silybum marianum [L.] Gaertn.) [abstract]. Integrative Cancer Therapies 6(2): 146–157.
• USDA, ARS, National Genetic Resources Program. Silybum marianum. Germplasm Resources Information Network - (GRIN) [Online Database]. National Germplasm Resources Laboratory, Beltsville, Maryland. Internet

Text © 2010 Rufino Osorio. All images copyrighted by their respective owners as indicated above.

Centaurea scabiosa – Greater Knapweed

Warning: Centaurea scabiosa has a high potential of becoming an invasive pest plant. It is included here only as an aid to identification and not to promote its cultivation in any way whatsoever.

Centaurea scabiosa Linnaeus is native to Siberia and Europe (USDA, ARS 2010) and is distinguished by its deeply lobed leaves and flower heads borne singly at the ends of the stems. The flower heads are subtended by broad, usually pinkish or purplish bracts with the margins fringed at the apex. The outer florets in each flower head are spreading, enlarged, and neuter (that is, sterile and not producing seeds). The plant is a perennial with thick, woody rootstocks that form a large, conspicuous rosette of leaves early in the year and from which arise flowering stems 1–3-feet tall, with the flowers present from July to August or September. Within its natural range, it favors chalky or limestone soils and the image above was taken by John Jordan in "south-west England on the edge of Salisbury Plain, a chalky hillside which used to be grazed pasture many years ago, but is now common land trimmed once a year." Ecologically, it is notable for attracting a wide variety of nectar- and pollen-seeking insects; as the sole source of food for the caterpillars of the case-bearing moth, Coleophora didymella Chrétien; and, in Britain, it is usually the only host of the parasitic plant, knapweed broomrape (Orobanche elatior Sutton) (Rumsey & Jury 1991:267). Besides greater knapweed, the plant is also known as greater centaury, hardhead, and ironhead, the latter two common names being a reference to the hard, solid flower heads (Grieve 1971:456).

Greater knapweed is now well established in Canada and throughout a wide range in the northern United States. Although it is definitely weedy, it is not currently listed as ecologically invasive in North America; however, due to the tendency of Centaurea species to become invasive pest plants in the northern United States and Canada, its cultivation should not be encouraged and plants growing in the proximity of natural areas should be closely observed and eliminated if seen to be spreading at the expense of the native flora. Greater knapweed might be mistaken for spotted knapweed, Centaurea stoebe L. ssp. micranthos (Gugler) Hayek (Centaurea maculosa auct. non Lam.), which is an invasive pest plant, since both plants have deeply lobed leaves. However, the latter has much smaller flower heads up to 1-inch wide, whereas greater knapweed has larger flower heads that are 2 inches wide or wider.

Observant readers may have noticed the red-spotted black moth at the base of the flower head. It is a burnet moth in the genus Zygaena, a group of day-flying moths that sequester cyanogenic glucosides from various members of the pea family that serve as food for the caterpillars, although George (2010) reports that these moths can also manufacture cyanogenic glucosides and do not need to obtain them from the larval food plants. The boldly patterened wings are an example of aposematic coloration, which is also known as warning coloration and serves as a visual cue to predators that the moth is distasteful and toxic.

USDA Distribution Map

References:

• George, H. 2010. Insects That Make Cyanide. suite101.com. Internet
• Grieve, M. 1971. A Modern Herbal, Volume 2. Mineola, New York: Dover Publications. Internet
• Rumsey, J. and S.L. Jury. 1991. An account of Orobanche L. in Britain and Ireland. Watsonia 18:257–295. Internet
• USDA, ARS, National Genetic Resources Program. 2010. Germplasm Resources Information Network (GRIN) Online Database. National Germplasm Resources Laboratory, Beltsville, Maryland. Internet

Image © 2010 by John Jordan and used by permission. Text © 2010 by Rufino Osorio.