28 de octubre de 2023

Vexing Vachellia: Ant "Acacia" in Costa Rica

According to the Missouri Botanical Garden's online Manual de Plantas de Costa Rica (see the Vachellia key), there are six species of Vachellia in Costa Rica: three obligately associated with "aggressive ants" (V. allenii, V. collinsii, V. cornigera) living in the stipular spines and three lacking mutualistic ants and the associated hollow spines (V. farnesiana, V. guanacastensis, V. ruddiae).

Since most "ant acacia" observations are just of leaves and spines, the nectaries on the leaves are the easiest way to tell these apart. Typical nectary traits for these species are:

Vachellia allenii (above) has many (up to 10), small, round nectaries at the leaf base. Note that they don't touch each other.
See also these V. allenii leaves and these V. allenii leaves.

Vachellia collinsii (above) with few (2-4), larger, round (pore-like) nectaries at the leaf base. Note that they often fuse together.
See also this V. collinsii observation.

Vachellia cornigera (above) with solitary, large, elongated (slit-like) nectary at the leaf base.

The Ant Acacia Details:

Vachellia allenii only occurs in "very moist" forests, and has flowers clustered in ball-like heads.

Vachellia collinsii and V. cornigera -- both "bullhorn acacias" -- are the tricky pair. They are less picky about habitat (forests from dry to very humid), both have their tiny flowers in fat, finger-like spikes, and they can be found in some of the same areas.

Vachellia collinsii: Groups of nectaries at the leaf bases. Round, pore-like nectaries are set in rounded raised areas at the base of each leaf (on the petiole) and are generally in groups of 2-3 (sometimes more; ocasionally just one if the leaf is young and small). There are sometimes small nectaries along the leaf rachis where pairs of pinnae connect, but it seems to be less common in this species than in the other two.
Individual leaflets have palmate venation: two main veins meet at the base of the leaflet. (This trait taken from the Flora de Nicaragua description).
Fruit (legume) with a short, less than 1 cm beak at the tip, spliting open along both sides when ripe.

Vachellia cornigera: Solitary nectaries at the leaf bases and along the rachis where pairs of pinnae connect. Elongated, slit-like nectaries are set in elongated, raised areas along the petiole and rachis. Usually, only one nectary at the base of the leaf (on the petiole), occasionally another small one nearby if the leaf is large.
Individual leaflets have pinnate venation: there is only one main vein running out from the bade of the leaflet. (This trait taken from the Flora de Nicaragua description).
Fruit (legume) with a long, 1-3 cm beak at the tip, and indehiscent (never opening) even when ripe.

Publicado el octubre 28, 2023 06:46 TARDE por m_whitson m_whitson | 1 comentario | Deja un comentario

15 de abril de 2023

Stealth Passifloraceae: Piriqueta versus Turnera

With five-petalled, often yellow flowers, Turnera and Piriqueta can easily be mistaken for members of the Malvaceae (like Sida). A closer look at a flower shows a three-part ovary and three styles. The floral formula 5-5-5-3 (5 sepals, petals, and stamens and 3 carpels) is unusual. (Part numbers usually match or are at least multiples of each other. Our Sida flower would have 5-5-lots-5 or 10).
This observation of Turnera sidoides shows the un-Sida-like flower with its unusual combination of 5 stamens and 3 stigmas .

A cross-section of a fruit (which matures to a three-segmented capsule) would show parietal placentation (placentas on the wall of the fruit rather than at its center). This is also an unusual trait.
The unusual features of Piriqueta and Turnera are typical for the passion flower family, which is where these taxa are now placed.

Turnera and Piriqueta both have pinnately-veined leaves, whereas similar-looking Malvaceae usually have at least slightly palmately-veined leaves (so perhaps 3-5 main veins joining at the base of the leaf).

Now for the tricky part: How do you tell these apart?

Unfortunately, there's no really easy way, particularly if you're working from a photo or two. There are differences in hair types on the foliage (Gonzalez & Arbo 2004), but also a good deal of overlap, and you need a microscope or serious closeups to see them. Turnera can have "stellate" trichomes, which range from a pair of branches joined at the base to clusters of up to eight rays. Piriqueta has porrect-stellate trichomes, with a cluster of rays at the base and a central point projecting up and out of the cluster (Gonzalez & Arbo 2004). Good luck with that.

Here are some key differences taken from Zelenski & Louzada (2019). Their paper on the Brazilian species of these genera has nice keys, thorough descriptions, and lovely line drawings -- well worth checking out.

Piriqueta leaves lack nectaries (sugar-secreting glands for bribes to ants). The flowers have inconspicuous to no bractioles (slender green projections at the base of the calyx). The 46 species of the genus are neotropical, with species native throughout the Americas (North, Central, South).
This observation of Piriqueta in flower shows the 5 stamens and 3 stigma feature, as well three-carpellate fruit and flower buds without bracteoles around them .

Turnera leaves often have nectaries (sugar-secreting glands for bribes to ants) along the petioles.
For example, Turnera subulata with extrafloral nectaries at the base of its leaf.
This observation of Turnera ulmifolia shows the extrafloral nectaries at the base the leaves, and also its three-carpellate fruit.
Finally, Turnera flowers have conspicuous bractioles (slender green projections at the base of the calyx). The 143 species of the genus are split between the neotropics and Africa.
This observation of Turnera diffusa shows extrafloral nectaries along the teeth of the leaf blade, and a bracteole on the side view of the flower.

Works Cited:

A. M. Gonzalez, M. M. Arbo, Trichome complement of Turnera and Piriqueta (Turneraceae), Botanical Journal of the Linnean Society, Volume 144, Issue 1, January 2004, Pages 85–97, https://doi.org/10.1111/j.0024-4074.2004.00229.x

Zelenski, A. and Louzada, R., 2019. The genera Turnera and Piriqueta (Passifloraceae sensu lato) in the state of Pernambuco, Brazil. Rodriguésia, 70. At https://doi.org/10.1590/2175-7860201970054

Publicado el abril 15, 2023 07:10 TARDE por m_whitson m_whitson | 0 comentarios | Deja un comentario

06 de agosto de 2022

Pesky Acanthaceae: How to tell Justicia croceochlamys from Schaueria calytricha

Justicia croceochlamys showing its distinctive anthers.
Justicia croceochlamys: Type locality is Colombia. Yellow calyx. White flowers to 4 cm long. Yellow bracts subtending the flowers to 3.0 cm long by 0.5 mm wide. Bractlets (?) can be longer.
Two anthers. Anthers two lobed, upper lobe attached at an angle (but with no tail), lower lobe attached parallel to filament and with a short tail.
From: The Acanthaceae of Colombia. Emery C. Leonard. 1958. In: Contributions from the United States National Herbarium, Volume 31, published by the Smithsonian Institution.
Full text available at the Biodiversity Heritage Library.
Page 532: Original species description in Latin.
Page 533: Illustration (including anther) & English description.

Schaueria calytricha: Type locality is Brazil. Yellow calyx. Yellow flowers to 4.5 cm long. Yellow bracts to 1.1 cm long by 1.0 mm wide.
Two anthers. Anthers two lobed, both lobes attached parallel to the filament and lacking tails.
From: Côrtes, Ana Luiza A., Thomas F. Daniel, and Alessandro Rapini. "Taxonomic revision of the genus Schaueria (Acanthaceae)." Plant Systematics and Evolution 302, no. 7 (2016): 819-851.
Full text available at Researchgate.
Page 826: Key to the species of Schaueria.
Page 820: Decsription of anthers found in the monophyletic Schaueria. Page 829, 831, 832: Description of S. calytricha. Page 830: Illustration of S. calytricha.

**Côrtes et al. (2016) recognize 14 species of Schaueria, three with yellow flowers and the others with white flowers. Many of these have relatively long, narrow calyx lobes or bracts among the flowers and iNaturalist has few (or no) photos of them, so be cautious when assigning species-level IDs.

Publicado el agosto 6, 2022 08:07 TARDE por m_whitson m_whitson | 1 comentario | Deja un comentario

17 de abril de 2022

The NKU Bio-Alumni Birds & Blooms Hike Returns

Saturday, April 16, 10:00 am

After being scotched by COVID restrictions in 2021 and being rained/snowed/sleeted out last Saturday, intrepid alumni of Northern Kentucky University's Biology Department and various NKU faculty met at Boone County's spectcular Middle Creek Park to see what we could see. We joked that it should be Birds, Blooms, & Boulders this year, since we had someone with geology background (Dr. Cooper-- former NKU student & current NKU faculty) join our normal compliment of botanist and ornithologist.

Finding a site that has both good bird-watching potential and diverse wildflowers to admire can be tricky, as birding opportunities peak here in May and the birds are easiest to see in open areas, while the wildflower show peaks in late April and is best under huge trees. Nonetheless, we pulled it off today.

Dr. Walters, our bird expert, had a list of over 30 species of birds encountered by the time we finished our 2 hour amble out along Middle Creek. We heard more than we saw, as we were under a canopy of giant sycamores (Platanus occidentalis) and poplars (Populus deltoides). The trees were alive with birdsong and woodpeckers drumming, everyone busily defending their territories. We heard Northern Parulas, Yellow-throated Warblers, Eastern Towhees, Redwing Blackbirds, and several distant hawk cries. We got a lovely closeup view of a male Northern Parula, saw a pair of Louisiana Waterthrushes and a kingfisher along the creek, spotted an American Kestrel drifting down to land in a treetop, and got a good look at a magnificent Pileated Woodpecker as it zipped over a clearing on its way to more large trees. We even startled up an astoundingly huge Great Blue Heron when we strayed too close to the creek.

Cute Northern Parula
A Red-eyed Male Towhee

We've had a cool spring, and the wildflowers weren't at their peak yet, but there was still color everywhere. The Blue Eyed Marys (Collinsia verna) were just beginning to tint the forest floor with sky blue. We spotted one white-flowered individual among all the blue and white bicolors. Both species of native Dicentra were in profuse bloom-- Dutchman's Breeches (D. culcullaria) and Squirrel Corn (D. canadensis) -- and they were joined by their pretty little yellow-flowered relative, the Pale Corydalis (C. flavula). The reddish-flowered toadshades (a sessile Trillium) were abundant, as was Mayapple (Podophyllum) and white-splashed waterleaf (Hydrophyllum) foliage. We saw blooming Spicebush (Lindera benzoin) and Paw-paw (Asimina triloba) branches covered in knobby brown bloom buds. The Woodland Phlox (P. divaricara) provided splashes of blue, lavender, and pinkish, and at least three species of violets (Viola spp.) added white, yellow, and purple punctuation. There were even a few Virginia Bluebells (Meternsia virginica), and of course plenty of Spring Beauty (Claytonia virginica).

Lovely Woodland Phlox
Virginia Bluebells Just Starting
Squirrel Corn Showing Off

The temperatures were cool but very pleasant, but combined with a mostly gray morning, they kept the insect activity muted. We saw a rusty orange butterfly (perhaps a Questionmark) and a little Spring Azure. We saw a fuzzy big bumblebee checking out some violets, and a tiny bee visiting chickweed flowers. Along the creek, there was one large dragonfly zipping around and one mayfly fluttering by.

On the banks of the creek, we admired 400+ million-year-old bryzoan fossils, rounded quartz pebbles and other smoothed rocks dropped off by glaciers, and what was perhaps a fossilized chunk of deer skull (coffee brown with age). In rocky stretches, you could see interesting little caddisfly larvae stuck to the flat stones, including some that made amazing little spiral shells that could pass for snails. The water was a little too cloudy today to easily spot darters, but I'm sure they were out there.

Strange Spiral Caddisflies

Overall, a great hike, and fun organisms to suit everyone's fancies.

Even Fungi

Publicado el abril 17, 2022 03:09 MAÑANA por m_whitson m_whitson | 7 observaciones | 0 comentarios | Deja un comentario