Return to Karoo National Botanic Garden

With visitors from the UK, a trip back to Karoo was planned so the unique desert flora and the gardens collections could be viewed. Getting to return to any site gives one an opportunity to explore in greater detail the vastness of the holdings and key into the nuances of a site. A more in-depth look at the horticultural practices was observed.

A key component of horticultural maintenance of any of South Africa’s flora is proper timing of watering and dormancy. The western and northern Cape regions experience the majority of rainfall in the winter months with a period of no rain throughout the hot summer months (October – May), in contrast to the eastern part of the country which experiences summer rainfall and plant dormancy and dry conditions during the cold winter months (April – September). Contrasting yet again some regions of the country, steady rainfall throughout the whole year can be expected and experienced. These are important details to keep in mind particularly when attempting to cultivate plants from each of these discrete regions. In Karoo Botanic one method to tackle this problem is to use colored labels to indicate watering regimes based on year. This gives the horticulturalist a visual cue as to which plants can be watered and when. This becomes particularly a concern for bulb species, which if watered in their non preferential season will cause them to rot in the ground during dormancy.

Water Coloring Chart

Blues label pegs in front (summer rainfall) green pegs in back ( all year rain fall)
Blues label pegs in front (summer rainfall) green pegs in back ( all year rainfall)

In small gardens like Stellenbosch where space is always a constraint, this pattern of winter and summer rainfall allows one to maximize on space. A pattern is established in the nurseries of maintaining “active”species on the tops of growing benches during their growing season. When plants go dormant, they are swapped down to the ground and will remain there, unwatered as the next season’s appropriate plants are raised onto the benches. This allows for total maximization of space and coordination of proper watering times.

Haworthia was once again explored in depth during the visit to Karoo. Many of the plants in the collection have been wild-collected across South Africa. In order to attempt to mimic natural settings where these plants were found, soils from these sites are also collected at the same time as sampling. This is also done with rocks of varying sizes. When the collections are planted out, they are placed in shallow trays (compared to large pots) with their native soils and rocks placed on top to act as a natural mulch and to create small habitat pockets for the specimens to grow. This method works reasonably well in the collections and allows for some of these unruly species to take to cultivation outside of their natural condition. One issue that has been noted with this soil practice is the “cementing” of soils that can occur after long periods of watering and high amounts of fines in native soils. Other Haworthia and succulent plant growers are known to use a more uniform soil mixture with less fines to prevent cementing as well as attempting to maintain more or less equal dry down periods for soil and schedule watering into a regime. To restore soil nutrients “Bounce back” is used to fertilize. Bounce back is a pelletized chicken manure commonly used in South Africa as a container plant feed. It is sprinkled onto the top of the soil and allowed to break down slowly with watering over time.

Haworthia herbacea var flaccida (Amazing cushion forming specimen) and rock mulch example behind
Haworthia herbacea var flaccida (Amazing cushion forming specimen) and rock mulch example behind
Haworthia sordida var. sordida – Red listed species (noted by orange boarder) with striking dark green foliage and rock mulch
Haworthia sordida var. sordida – Red listed species (noted by orange boarder) with striking dark green foliage and rock mulch

Now for a whole bunch of unusual specimens

a beautiful clump forming Haworthia
a beautiful clump forming Haworthia

Haworthia mutica var. mutica 1

Haworthia mutica var. mutica 2 – An small single forming Haworthia extremely rare to find in the wild. Few collections are known to exhist, but there are rumored to be ones in peoples collections in the USA- Keep your eyes and get a leaf cutting if you come across it.
Haworthia mutica var. mutica 2 – An small single forming Haworthia extremely rare to find in the wild. Few collections are known to exist, but there are rumored to be ones in people’s collections in the USA- Keep your eyes out and get a leaf cutting if you come across it.
Haworthia blackburniae var graminifolia  - This species is red listed and of note because of its unusual fine foliage that appears of that of a graminoid (grass)
Haworthia blackburniae var graminifolia – This species is red listed and of note because of its unusually fine foliage that appears as that of a graminoid (grass)

And some more weird ones

yup its just as weird as it looks
Yup, it’s just as weird as it looks

Gasteria bicolor var. bicolor 2

Duvalia parvifolia  flower

Portulacaceae Avonia quinaria subsp. Quinaria – if you zoom into the foliage, fine scales can be observed and light translucent sheeth.
Portulacaceae Avonia quinaria subsp. Quinaria – if you zoom into the foliage, fine scales can be observed and light translucent sheaths.

Portulacaceae Avonia papyracea subsp. namaensis

And on to the Aizoaceaes – A family with nearly all of its diversity native to South Africa

Lapidaria margaretae  2
Lapidaria margaretae
Fenestraria rhopalophylla subsp. Aurantiaca – a clump forming, striking and red listed species
Fenestraria rhopalophylla subsp. Aurantiaca – a clump forming, striking and red listed species
Moon rocks? No silly just Conophytum burgeri, who would make that mistake?
Moon rocks? No silly, just Conophytum burgeri, who would make that mistake?

Conophytum obcordellum subsp. Obcordellum – a variegated conophytum

Off into the gardens once again. During this walk we mostly rambled around the natural areas surrounding the garden which will receive native plantings, but are not a priority for maintenance since the landscape is “natural.”

Welwitchia merabillis male cones
Welwitchia merabillis male cones

Pachypodium namaquanum flower dissected

Pachypodium namaquanum
Pachypodium namaquanum
Pachypodium namaquanum flower
Pachypodium namaquanum flower
Pachypodium namaquanum flower 1
Pachypodium namaquanum flower

Pachypodium namaquanum flower disected

As we strolled around the landscape a great abundance of Euphorbia mauritanica was observed as playing a large part in the shrub component of the landscape. One member of our party noted a rather putrid smell wafting from the air, a smell that might cause the casual visitor to quickly vacate the area had quite the opposite effect on the group of botanists. Flurried excitement gave way to scurried searching around the bases of the Euphorbias in attempts to find the source of the foul oder. Before long the source of the scent was located, and protruding from the ground was the freaky flowering parasitic plant known as Hydnora Africana. Known as a carrion flower emitting the smell of rotting flesh to attract pollinators, this parasitic plant has one of the more unusual blooms encountered in the wild. When peering into the bloom we were lucky enough to find beetles scurrying, pollinating and attempting to escape the plant’s grasp.

Euphorbia mauritanica
Euphorbia mauritanica
Hedorah africana
Hedorah africana
Hedorah africana
Hedorah africana
Hedorah africana
Hedorah africana
Alex summers going in for the smell
Alex Summers (Cambridge University Botanic Garden) going in for the smell
Aaristolochia macrophylla
Hedorah africana – Full dissection of root 

hydnor01

Hydrnoa Africana belongs to the plant order Piperales family Hydnoraceae. A most unusual family, it currently sits on its own with close relationship to Aristolochiaceae. According to the Angiosperm Phylogney Group, Hydrnoraeae will likely end up being lumped into Aristolochiaceae eventually.

(http://www.mobot.org/MOBOT/research/APweb/)

The order Piperales includes three families; Aristolochiaceae, Hydnoraceae and Saururaceae. A quick trip down to the Plantations can allow you to explore a few members of this order right on the Cornell campus. Come early summer the unusual blooms of Aristolocheae macrophylla (http://woodyplants.cals.cornell.edu/plant/27) can be observed growing on the arching entrance trellis of the vegetable garden next to the McClintock Shed. In late August another member of the order Saururus cernuus can be observed on the first bridge at the bottom of the slope as one heads east across the road from the Lewis Education Building, down the path and slope heading east towards the Mundy Wild Flower Garden.

Aristelochia macrophyla
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