The Shrubs of Iridaceae

Nivenia corymbosa

Nivenia corymbosa

Did you know there are shrubs in the iris family? I didn't either until quite recently. I had the distinct honor of getting to tour the collections of Martin Grantham, a resident of the Bay Area and quite possibly the most talented horticulturist I have ever met. Martin has had quite a bit of luck with these plants and because of this, I was able to meet a handful of them growing quite happily in large containers. There are some things in life that your brain just simply isn't prepared to take in. The shrubby iriads are one of them.

The true shrubby species all hail from a subfamily of Iridaceae coined Nivenioideae. This is not a single grouping of all shrubby genera. It contains other genera that look a lot more like what we would consider an iris. Nivenioideae as a whole is considered to be pretty derived for the iris family, with the shrubby species serving as an excellent example of how bizarrely unique the subfamily really is. In total, there are three genera of shrubby iriads - Klattia, Nivenia, and Witsenia, all of which are native to South Africa. Klattia and Nivenia contain a small handful of species whereas Witsenia has only a single representative.

Nivenia stokoei

Nivenia stokoei

Once you get past the initial shock and awe of what you have just laid eyes on, their membership in the iris family becomes a bit more apparent. Though there is great variation in size, the species I encountered all looked roughly like long, slender sticks with multiple iris-like fans of leaves jutting out. Like most members of the family, the flowers of this group are spectacular. In the wild they are visited by long tongue bees and flies.

Klattia partita

Klattia partita

Overall this group is poorly understood. Some molecular phylogenetic work has been performed but it is by no means concrete. More attention may result in either the addition or subtraction of species. The most thorough treatment on the shrubby iriads comes from a monograph written by Dr. Peter Goldblatt as well as a handful of horticultural articles written by those lucky enough to have had some success in growing these plants (see Martin's essay on his experiences - http://bit.ly/2pStMZ4).

Klattia stokoei

Klattia stokoei

Like most of South Africa's unique flora, these plants are at threatened by habitat destruction, invasive species, and climate change. Luckily many of these species have caught the attention of folks like Martin who have put in the time and dedication into understanding their germination and growth requirements.

Seeing these plants in person was breathtaking. Not only was I completely flabbergasted at their appearance, the fact that plants like this exist is a testament to the wild diversity of life this planet supports. I never tire of meeting new plant species and this is one encounter I won't soon forget. Just when you think you are starting to understand plant diversity, plants like these show up to remind you that you have just barely scratched the surface.

Photo Credit: [1] [2]


Further Reading: [1] [2]

The Plant That Grows a Perch

For flowering plants, entering into an evolutionary relationship with birds as pollinators can be a costly endeavor. It can take a lot of energy to coax birds to their blossoms. On the whole, bird pollinated flowers are generally larger, sturdier, and produce more nectar. They tend to invest heavily in pigmentation. The plants themselves are often more robust as well. Unlike hummingbirds, which usually hover as they feed, other nectar-feeding birds require a perch. Often this is simply a stout branch or a stem, however, a plant endemic to South Africa takes bird perches to a whole new level - it grows one. 

Meet the rat's tail (Babiana ringens). Though not readily apparent, this bizarre looking plant is a member of the iris family. It is endemic to the Cape Province of South Africa where it can be found growing in sandy soils. It produces a fan of erect, grass-like leaves and, when conditions are right, a side branch full of red tubular flowers. This is when things get a bit strange. 

From that flowering stalk emerges a much longer stalk that is said to resemble the tail of a rat, earning this plant its common name. This stalk rises well above the rest of the flowers. If you look closely at the tip of this stalk you will quickly realize this is yet another flower stalk, though this one is sterile. Such a stalk may seem like a strange structure for this plant to produce until you consider its pollinators. 

The rat's tail has entered into an evolutionary relationship with a species of bird known as the malachite sunbird (Nectarina femosa). To access the nectar within, the malachite sunbird can't simply walk up to and shove its face down into the flowers. Instead, it must access them from above. To do so, it perches itself on the rigid sterile flower stalk. Once in position, the malachite sunbird can dip its long, down-curved beak directly into the flowers. This is exactly what the plant requires. In this perched position, pollen is brushed all over its chest. 

babssunny.jpg

Researchers wanted to know how obligate this relationship really was. By removing the perch on selected plants, they were able to demonstrate a reduction in pollination success . Specifically, male sunbirds were less likely to visit plants without the perch stalk. Although these plants are capable of self pollinating, like any sexually reproducing organism, outcrossing is the key to success. By offering the birds a sturdy perch allowing them exclusive access to their nectar, the plants guarantee sunbird fidelity.  

Photo Credits: [1] [2]

Further Reading: [1]