Bauhinia and Hibiscus: A Comparison of Floral Reproduction

This posting is a response to the numerous hits made on a previous posting featuring the Non invasive Bauhinia tree. It seems that the interest lies in its reproductive nature. The purpose of this post is to improve the understanding of plant biology through comparative anatomy.

The title image shows the Bauhinia (blakeana ) on the left and the Florida native scarlet rosemallow (Hibiscus coccineus) on the right. I photographed the Bauhinia in the roadway median of our neighborhood. I photographed and display the scarlet rosemallow because it is such a stunning finding in the fresh water marshes of the Corkscrew Nature Preserve in SW Florida. It also shows that it is not a cultivar but it can self propagate without human intervention. Both plants are eye candy that must be appreciated in their out-of-door surroundings. In our community we have domesticated tropical hibiscus which are close relatives to the wild scarlet hibiscus

These two blossoming plants attract loads of attention. The Hong Kong orchid (Bauhinia blakeana ) and the cultivated tropical Hibiscus (Malvaceae) produce wonderful, flamboyant, visually attractive flowers. They are planted throughout our community. Additionally, these blooms have great staying power lasting for many months. Their flowering period stretches anywhere from eight to ten months, from September to June. They have, however, remarkably different reproductive powers. To reveal the secret of these two plants this posting compares the gross and micro anatomy of their two flowers.

A detailed diagram of a Bauhinia flower labeled with its anatomical parts, including bud, petal, sepal, stamen, pistil, ovary, style, and stigma, showcasing the flower's structure. — Bauhinia blossom with some pettals removed

Diagram labeling parts of a hibiscus flower including the stamen, ovary, style, stigma, petal, and sepal, accompanied by lush green leaves and a bud. — Hibiscus blossom with no petals removed

Gross and micro dissection reveals the major difference in the reproductive capacity of the these two perfect flowers. Dissection and microscopic examination of the ovaries shows that the hibiscus has ovaries while the bauhinia has no trace of ovules. It is unable to sexually reproduce.

Diagram illustrating the anatomy of a Bauhinia flower, highlighting its various parts including petal, sepal, stamen, anther, filament, ovary, style, stigma, and pistil. The text indicates that the flower is perfect but sterile, with no ovules or seeds. — This is a full dissection of the *Bauhinia × blakeana* blossom. Look at the top left images. You can see that under microscopic examination there are no ovaries within the ovary. This plant is infertile.

Anatomy diagram of a hibiscus flower, illustrating the components like the ovary, stigma, stamen, and petals, labeled with descriptions to explain its reproductive functions. — This is a full dissection of the Hibiscus blossom. Look at the top left images. You can see that under microscopic examination there are ovules within the ovary. This plant can produce seeds. It is fertile.

The five-petaled blossoms of Bauhinia plants are known as “perfect flowers,” because each individual bloom contains both female and male parts. Some varieties of the Bauhinia flower, such as the widely cultivated Hong Kong Orchid Tree (Bauhinia × blakeana), are known to be sterile. Bauhinia are monoecious, which means “single house”. This designation describes the dual sexual capacity in a single flower. The flowers can self pollinate or fertilize with pollen from another plant. The flowers attract pollinators such as hummingbirds, bees, butterflies, and more. Bauhinia × blakeana‘s sterility is due to its hybridization. Bauhinia blakeana is the result of conjugation of the very similar species Bauhinia purpurea ( Purple Camel’s Foot) and Bauhinia variegata ( Camel’s Foot Tree). Both of these are exotic species according to the Hong Kong Herbarium. The parent plants have partially overlapping flowering periods and geographical habitats, and the same range of bee and butterfly species as pollinators. Interbreeding Bauhinia purpurea and Bauhinia variegata is probable. The resulting triploidy of this plant has probably rendered this varietal sterile. The plants you see today are clones of the same flowers seen by Hongkongers more than a century ago. They are propagated asexually through cultivation of stem cuttings.

The Hibiscus is also considered a perfect flower which actually produces viable seeds. The hibiscus is a genus of flowering plants known for their large, showy flowers, belonging to the mallow family (Malvaceae). Fertilization of these plants is complex. Pollination may fail because of these five prerogatives.

Self-Pollination: Some hibiscus varieties are self-pollinating. This can make it difficult to cross-pollinate them.
Timing: Hibiscus flowers are only receptive to pollen for a short period, usually just a few hours.
Pollen Viability: Hibiscus pollen can lose its viability quickly.
Stigma Receptivity: The stigma needs to be receptive to pollen. The stigma, gateway to the ovarian, might not be receptive at the same time the pollen is viable.
Germination: Seeds take 12 to 24 months to bloom.

The hundreds of species of hibiscus are generated through human intervention of the pollination. Tropical hibiscus are propagated sexually from seeds or asexually from stem cuttings or plant division. In carefully controlled environments and with delicate, patient effort botinists have hybridized the tropical hibiscus to make hundreds of beautiful new varieties. The new plant varieties are propagated from cuttings or division to produced plants which are clones of their parents.

Illustration explaining hormonal fertility signals in plants during pollination, detailing four key hormones involved in the process. — In addition to timing, these four hormonal obstacles must be passed in the carpel for signaling a specific selection of pollen appropriate for germination of ovules in these species.

DISCUSSION of FINDINGS:

This is not a thorough scientific data collection. Three samples of blossoms from each of two trees were collected for a total sample size of six. All of the samples were made on the same day in April, 2020. There were no major local meteorological events for the year preceding this observation. There were no observations of the viability of the observed polled during this observation. Further study should be done to give this a high level of confidence of the conclusions.

SUMMARY:

In Florida the Bauhinia × blakeana and Hibiscus plants thrive and are found in almost all of the cultivated communities and household gardens. They are well tolerated but stable non-native species. Because of their reproductive limitations they are not invasive. We can feast our eyes on this banquet of form and color without fear of damaging the environment.

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#Bauhinia #Hibiscus #reproduction #flowers #invasives #anatomy #seeds #sterile #

June 21, 2025

Wildflowers in SW Florida – Xeric Group

This group of flower images were made from observations during the last February, March and April. This is the second of a series on wildflowers of SWFL. These images represent some of the flowers which were seen in three distinct environments: uplands, pine and saw palmetto flats and costal flats. There is some crossover of plants which may be seen in multiple environments. For organizational simplicity the images have been separated into two groups: those that grow better in moist soil areas are in the mesic group, those that grow better in dryer soils are listed in the dry mesic and xeric group.

The images which are used here for illustration show the beauty and diversity of the native plants. As a supplement to these images there is a spread sheet posted under PAGES of this site which lists the plant growing requirements. If you wish, this information may be used to assist in selection of plants which you could plant in your own SWFL community or home garden. The images are associated with a Fig #. That number is the data key number listed in the first (Left) column of the spread sheet. Use that number to correlate the image to the data.

The featured image is Figure 22. Pinebarren Goldenrod (Solidago fistulosa)

Figure 2. Nettle Leaf (*Salvia urticifolia)*

Figure 3 Florida Tickseed (*Coreopsis floridana*)

Figure 4 Nuttall’s Thistle (*Cirsium nuttallii)*

Figure 6. Simond’s Aster, (*symphyotrichum simmondsii)*

Figure 7 Southeastern Sunflower (*Helianthus agrestis*)

Figure 20 Flag pawpaw (*Asimina obovate*)

Figure 24 Tickseed (*Coreopsis Leavenworthii*)

Figure 26 Sweetscent (*Pluchea odorata*)

Figure 29. Rabbit bells (*Crotalaria rotundifolia*)

Fig 38. Rusty Lionia (*Lyonia ferruginea*)

There are definitely fewer flowering plants in the dry group. These flowers are less flamboyant in color, shape and size. The dominant chromas are in the middle of the visible light spectrum, the hues are in the lighter range and the values are in the middle zones. Their growth in single plants tend to be in dense florets and panicles. As groups of plants they tend to be distributed in patches of the landscape. This may be related to their propagation frequently by seeding.

For the gardeners be sure to check out the supplement to these images on the spread sheet in the Pages post on this site titled findings/Wildflowers in SWFL

References:

Real Florida Gardeners Guide lists native nurseries

Guide for Choosing Native Plants by Florida Wildflower Foundation

Pruning Notes for Native Plants by Grounded Solutions

Getting into the “Weeds:” An Introduction to Common Lawn Plants and Their Ecological Benefits

Plant This Not That book

Attracting Butterflies with Wildflowers by Florida Wildflower Foundation

Full Plant Reference List

Native Florida Landscape – Florida treasure coast

Estero preserve

Florida Soil

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April 18, 2024

Wildflowers in SW Florida – Wet, Mesic Group

Here are images of flowers made from observations during the last three months. This is one of a series on native wildflowers of SWFL. These images represent some of the flowers which were seen in three distinct environments: uplands, pine and saw palmetto flats and costal flats. There is some crossover of plants which may be seen in multiple environments. For organizational simplicity the images have been separated into two groups: those that grow better in moist soil areas are in the mesic group. Those that grow better in dryer soils are listed in the xeric group.

The featured image is a Dixi Iris and a visiting Monarch butterfly

The images which are used here for illustration show the beauty and diversity of the native plants. As a supplement to these images is a spread sheet in the Pages post on this site titled findings/Wildflowers in SWFL. which lists the plant growing requirements. If you wish, this information may be used to assist in selection of plants which you could use in your own SWFL community or home garden. The images are associated with a Fig #. That number is the data key number listed in the first (left) column of the spread sheet. Use that number to correlate the image to the data.

Fig1. Water Pimpernel; Limewater Brookweed (*Samolus ebracteatus)*

Fig 8. Winged loosestrife (*Lythrum alatum*)

Fig 9. String Lily (*Crinum americanum)*

Figure 10. Scarlet hibiscus (*Hibiscus coccineus*)

Fig 11. Pickelelweed (*Pontederia cordata*)

Fig 12. Lizard’s tail (*Saururus cernuus*)

Figure 13. Mexican primrose willow, (*Ludwigia octovalvis*) INVASIVE!

Fig 14. Dancing Lady Ginger, (*Globba winitii*)

Fig 17. Spanish needles (*Bidens alba, Asteraceae*)

Figure 21. Tickseed (*Coreopsis floridana) State of Florida Flower*

Figure 23. Big yellow milkwort (*Polygala rugelii)*

Fig 27. Water Hyssop or Herb-of-Grace (*Bacopa monnieri*)

Fig 28. Salt marsh morning glory (Ipomoea sagittate)

Figure 30. Grassy Arrowhead (*Sagittaria graminia*)

Figure 31. Fragrant Flatsedge (Cyperus odoratus)

Fig 32. Saw Grass (*Cladium jamaicense*)

Fig 33. Coastalplain St.John’s-Wort (*Hypericum Brachyphyllum)*

Fig 34. Princess flower (*Tibouchina grandiflora*) (Not native, escaped house plant)

Fig 35. Brazilian Plume (*Justicia carnea)* (Not native, escaped house plant)

Fig 36. Orange Milkwort – Polygala lutea

FIG 38. Rusty Lyonia (*Lyonia ferruginea*)

Fig 39. Meadowsweet (*Spiraea cantoniensis*)

There are definitely more flowering plants in the music group than the xeric. These flowers are flamboyant in color, shape and size. The dominant chromas are in the ends of the visible light spectrum, the hues are in the more saturated range, the values are in all zones and they may be multi-chromatic. Their growth as single plants tend to one bloom. As groups of plants they tend to be distributed in patches of the landscape. This may be related to their propagation frequently by rhizomes.

For the gardeners be sure to check out the excellent PAGES Excel spread sheet for the Wildflowers of SWFL data on these beautiful images.

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