tropical botany

Neuburgia + meanders vol. I

Although the text part has been ready for about two weeks, I was simply too lazy to upload a photo of my Ochrosia elliptica seeds. But now that it’s done, I guess it’s all finally ready to take off.

Nature gods know how long it is. Oh dear, I certainly am putting much heart into this, haha. This time, the sources are provided directly with pictures - just click on them. OK. Neuburgia. Neuburgia. Let’s start with simple stuff.

Neuburgia Blume is placed in the Loganiaceae family (13 genera according to APG III) of the plant order Gentianales. The genus is closely connected to other loganiaceous genera Gardneria and Strychnos. These two genera possess the enzymes to construct some strictosidine-derived alkaloids like strychnine (mostly S. nux-vomica), toxiferine (mostly S. toxifera) or gardfloramine (G. ovata, for example). This information could possibly indicate that plants belonging to Neuburgia also have this biochemical competence and, thus, are able to produce those complex, strictosidine-derived structures (could they get more perfect?). There is a study that proved the presence of some kind of alkaloids in Neuburgia, but none of the details were further sought after. It is almost a given, though, that those beauties contain iridoids. Those terpenoid chemicals can be quite like markers in plant systematics.

Strictosidine synthase… Hello, are you there? Deep inside Neuburgia tissues?

All five families of Gentianales contain iridoids, though those compounds are not an exclusive feature of the order. Well, they have been even found in animal kingdom! But plants, please…

Here (scroll down a bit to 28.2.2)

Iridoids - chemical skeletons.

Looks like those lovely terpenoid structures are rather unique to certain asterid groups, not encountered in other systematic groups. That’s why it’s almost a given (99,9%) iridoids are to be encountered in tissues of Neuburgia specimens. Why almost? Because I haven’t been able to trace a single study pointing out to this; if taxonomy is anything to go by, then it’s very, very likely that Neuburgia plants manipulate a geraniol molecule further to iridoid structures.

If one’s looking for opposite leaves and corollas composed of a quintet of fused petals, then Gentianales should be the destination. Although there are some exceptions when it comes to leaf arrangement (rarely alternate or forming a whorl) or floral symmetry (sometimes 4-merous or even more complex sets like in Anthocleista or Potalia).

Anthocleista grandiflora ain’t got time for 5-merous flowers.

Why was Neuburgia placed in Loganiaceae? Why not Gentianaceae, Rubiaceae, Apocynaceae or Gelsemiaceae?
Apocynaceae would be definitely out of question, since latex presence is one of the most characteristic features of the family (laticiferous); it’s something that Neuburgia lacks (non-laticiferous). Apparently, though, Neuburgia was once regarded as a genus belonging to Apocynaceae (click). Scientists speak of some similarities between fruits of Neuburgia and those of some apocynaceous genera like Cerbera and Ochrosia. This is enough information for me to conclude that the seed extraction process would be very easy… NOT!

Alstonia scholaris (Apocynaceae). No chances of getting here without latex, sorry.

I have tried once in my life with Ochrosia elliptica ‘seeds’. I’m led to believe that what was sold to me as a 'seed’ was in reality a hard, stony endocarp with an actual seed (usually) buried inside, in some sort of a pocket. It was quite a task to separate the halves of the woody boxes. Out of 10 of those stones I think 8 had seeds and the remaining 2 were just empty. Well, sometimes it happens… The real misfortune happened later, when some mould started consuming the seeds, thus rendering the experiment a failure. Boo! Well, after those two and a half years some experience in-flow must have occured… So, Neuburgia fruits, behold! :)

Ochrosia elliptica: these are not seeds, rather endocarps

Ochrosia elliptica: these are seeds (with some sand grains)

The other families would not be appropriate due to other anatomical and morphological differences. Neuburgia from distance would surely look like one of rubiaceous trees with its big opposite leaves and big stipules. But on close examination, the flowers would reveal their superior ovary, thus rendering the inclusion of Neuburgia in Rubiaceae very dubious. Even closer, more detailed and microscope-assisted look would reveal the presence of internal phloem. This character ultimately rules out any possibility for Neuburgia to be included in Rubiaceae. Rubiaceous plants lack internal phloem, singling them out of the entire Gentianales clade.

Pentas lanceolata (Rubiaceae) and its inferior ovary; Neuburgia has superior ovaries (and not just ovaries as far as I’m concerned).

Flowers of Gentianaceae possess naked corollas, without any hair structures. Neuburgia wouldn’t fit here, having a ring of hair in corolla throat. This site also notes a different petal lobes alingment inside a floral bud for Loganiaceae and Gentianaceae. Perhaps stipular sheath in Neuburgia is another conflicting factor.

Gentiana dinarica (Gentianaceae). We’re glabrous, honey - you’re out!

And so we’re left with Gelsemiaceae and Loganiaceae. Why not Gelsemiaceae? Perhaps this site again would help big time with answering. I have done some research and it looks like stigmas are in Loganiaceae 1- or 2-lobed, while in Gelsemiaceae it is 4-lobed. Moreover, loganiaceous plants are usually homostylous (in contrast to gelsemiaceous specimens which are nearly always heterostylous.

Gelsemium sempervirens (Gelsemiaceae). 4-lobed stigmas?! Still not home…

I’m sure there are other very important differences, but I haven’t dug this deep yet. Anyway, those above could be enough, I think!

OK, let the unveiling begin. Where exactly can we encounter Neuburgia plants? Let’s refer to some information from old literature. I’m picking Flora Malesiana and Journal of the Arnold Arboretum. Ah, one more thing! Neuburgia has also some other botanical names, which are no longer used. Officially:

Neuburgia Blume = Couthovia A.Gray = Crateriphytum Scheff. ex Koord.

(click! - explanation behind Blume, A.Gray and Scheff. ex. Koord)
(click! - plant names and their respective authours)

Karl Ludwig von Blume, the man that 'invented’ Neuburgia. No wonder it sounds quite German(ic). What about its ethymology, though? Could this be?

All plants have those official gowns, but your everyday Joes & Janes would rather put them in casual clothes. When not in scientific glamour, these would simply look like Neuburgia, Couthovia and Crateriphytum. More friendly, aren’t they? OK, back on topic - Neuburgia and its natural distribution (remember, Neuburgia = Couthovia = Crateriphytum):

“Centering in New Guinea, the range of Couthovia extends from the Philippines and Celebes to Micronesia, New Caledonia, the New Hebrides, and Fiji, where six endemic species terminate it.”

(Journal of the Arnold Arboretum, V.36 1955, page 287)

“[…] East Malaysia* (from the Philippines and Celebes to New Guinea), Carolines, Solomons, New Hebrides, New Caledonia, and the Fiji Is.”

(Flora Malesiana, page 363)

* there are two similiar words - Malesia and Malaysia. Malesia is a biogeographical region, while the latter is a country. The authors rather had 'Malesia’ in mind. These pieces of literature are old, however, and certain names and words might have had their meaning altered, so…

Malesia, a biogeographical region.

The heart of Neuburgia distribution seems to be associated predominantly with Melanesia then. Please refer to this map:

It’s quite shocking that the genus hasn’t made it further east, to Polynesia. Tongan Islands aren’t this far from Fiji archipelagos. Well, perhaps by now, those plants have already reached Polynesian shores. The fruit anatomy suggests that water might play a role in its dispersal, as stated in Flora Malesiana. OK, the general distribution area of Neuburgia is known already. Let’s proceed to some general characteristics and include some visuals along with words:

A fruiting Neuburgia novocaledonica specimen, New Caledonia.

Neuburgia are generally trees or shrubs, being even able to catch birds that fly 30m high! In other words, they can form some medium-sized to quite large trees.

Neuburgia novocaledonica specimen in cultivation, New Caledonia.

Neuburgia novocaledonica possesses beautiful broadly elliptic (to obovate) leaves that are arranged oppositely and joined by a distinct stipule. This stipular sheath is torn apart as the stem matures and increases in width. Lovin’ it!

Interpetiolar sheath of Neuburgia novocaledonica.

Neuburgia has beautifully designed inflorescences. These are thyrsoids, which are further complimented by symmetrical, 5-merous and very elegant small flowers!

Thyrsoids with lots of buds and some truly cosmic flowers of Neuburgia novocaledonica.

Tiny flowers are bisexual, though I have no idea whether these are self-compatible or not. The five petals are fused partially, forming a corolla tube. The same is true for sepals.

Close-up of the flowers. I cannot get over their immaculate beauty!

What follows flowering (if stigmas have received enough pollen, that is) is fruiting. When in fruit, Neuburgia could resemble a certain temperate fruit - pear.

Pears? Not? The resemblence is quite striking, isn’t it? The colouring is off, though (unless there are some white pear cultivars I haven’t heard off).

They might look like pears, but their anatomy is different. Neuburgia forms drupes, while Pyrus trees form pomes, a kind of fruit encountered in certain taxa of Rosaceae.

I shall elaborate more on Neuburgia anatomy and morphology in upcoming posts, providing as many details as I can find. I guess it’s enough for now. :)

Don’t care about past.
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Nature's Radar

Are you sitting down? You may want to before you read this. The relationship I am about to tell you about is pretty amazing. Coevolution is never a dull topic and the following example may be one of the coolest in the living world. 

Meet Marcgravia evenia. This vining plant species is native to Cuba and, like other members of its genus, relies on bats for pollination. This is nothing new. Many plant species utilize bats as pollen vectors. Bat pollinated flowers are often quite fragrant, using powerful odors to tap into the bats keen sense of smell. Marcgravia evenia is different though. This tropical vine taps into another batty sense, echolocation. 

Right above the flowers is a dish-shaped leaf. This leaf functions as a reflector for the bats sonar! Indeed, when tested, bats were twice as likely to find plants with these dish-shaped leaves than they were if the leaves were removed. This is an incredible coevolutionary adaptation! Because the vines are rare in the wild, anything that would increase the likelihood of a bat visitation would incur a considerable selective advantage. The dish-shaped leaves do just that. According to the authors of the paper, “the leaf’s echoes fulfilled requirements for an effective beacon, that is, they were strong, multidirectional, and had a recognizable invariant echo signature.” Nature never fails to amaze!

Photo Credit: Ralph Simon

Further Reading: