Friday, September 13, 2013

The world outside your window

Welcome  back to another episode of LITFM, normally there would be a longer intro but the topic being tackled covers a detailed subject with examples and space is tight so, enjoy this look into biological diversity.
Today’s topic of discussion is the basic concept of biological diversity. The  reasoning to speak about this here comes from a number of conversations at the farmer’s market booth over the summer. I hear a lot of folks saying something like ‘there’s more than one type of…” which amazes me. When you think about it the aforementioned is a surprising statement because at the supermarket there are many types of produce often side by side to match personal preferences. This sort of thing makes me wonder why it’s so surprising to some out there that there are differing types of plants otherwise. Case in point, one of our most common medicinal plants Aloe barbadensis or Aloe Vera is well known but other varieties in the family are relative unknowns.

So let’s start with the biology of our example plant and address the idea of biological diversity. Now the aloe is a good example of a species that is well adapted to its climate which is for the most part arid regions of Africa. This of course means that the Aloes have several critical survival features for the climate. If you ever were to dig up a aloe and remove all the soil you would see a rather good portrait of a traditional arid climate succulent plant. The main feature below the surface is the thick primary root which is more or less a tap root that has evolved to push through dry desert soil to find moisture. If the Aloe you’re looking at was pot bound you might see a number of thick roots all of which were geared towards finding moisture and nutrient despite what the arid climate’s soil conditions might be. Above ground you would see the central growing point or the crown, and a number of alternating pattern triangular leaves each more of then then not swollen with fluids. Those fluids in the leaves includes a slimy mucilage that acts as a counter for water loss due to damage and as a predatory deterrent.  If you can imagine having a mouth full of something slippery and terrible tasting like dish soap you sort of get the idea. It’s not pleasant and while more complex animals might have means to handle this, in most cases insect pests are undone by it. This feature in turn ensures the species survival, despite being a biological oddity to us and indeed part of the plants medicinal allure.

All of this is an adaptation to handle the specific climate in which the aloe grows specifically arid places where soil quality and moisture are at a premium. The aloe itself reproduces in two ways, by flower and by producing clones of itself. The first part about flowers is pretty standard; the aloe will eventually bear a group of tube shaped flowers in a long stalk. If pollenated these flowers will produce some form of fruiting body which then disperses the offspring of the plant. Alternately aloe is also able to clone itself by producing vegetative structures called offsets or ‘pups’. Thes mini aloes are connected to the mother plant by little underground stems and generally serve to expend the area the central plant occupies while also acting as a very efficient means to out-compete competition. But this is not all; these offsets if separated from the mother plant say by the mother plant being eaten; will continue on and as noted prior be exact genetic copies of the mother. Some variation on this asexual reproductive aspect is seen across the entire cactus and succulent spectrum. For instance stressed rhipsalis and Christmas cacti will often ‘shatter’ and shed their fleshy pads or branches as a means to get the branches to hopefully land in another pocket of soil thus keeping the species alive. Likewise the Prickly pear under certain conditions will shed its fleshy pads to perform the same action. The massive Sanguaro cactus will occasionally shed its ‘arms’ to do the same with odd results.  So these succulents are biologically set to survive and do so just fine without our intervention.

This leads to a question, how much diversity could there be in one given family if the core stuff is rather efficient already? Well you would be surprised, as with song birds and their amazing variety of colored plumage, plants are equally adapted to their specific niche and thus numerous varieties exist. So lets take a look at what variety is out there in the aloe family.

Aloe barbadensis - Aloe Vera
Your typical medicinal aloe much like a head of cabbage is the poster child for the family because we know it so well. To the point that the natural populations of it may not exist anymore. This is the sad part of the Aloe family’s story, it’s most known member is grown exclusively in cultivation as no known natural stands of Aloe Vera are known to exist. On the other hand in cultivation aloe has gone farther than would otherwise be possible and to climates far beyond the native range of the originating plant.

Aloe ciliaris – Climbing Aloe
Climbing aloe is an example of an regional adaptation. Unlike Aloe Vera climbing aloe grows less in arid places but within the thickets of the Eastern Cape of Africa. In order to climb this aloe has developed leaves that are hook like in shape allowing it to rapidly use other plants as support to get to the top of the thorny thickets it grows in. Furthermore it is noted as being the fastest growing aloe which is another adaptation to ensure its survival in a densely competitive environment.

Aloe deltoideodonta – Stemless Aloe
It’s hard to say why stem less aloe is how it is but the shortened stems could be a surface area reduction adaptation for an exceedingly hot climate. Less stem means less hight means less area exposed to transpiration. The odd checker board pattern on the leaves could be a form of mimicry designed to break up the plant’s shape as it might look a bit like gravel or coarse sand at a glance.

Aloe dorotheae – Sunset Aloe
Sunset aloe is critically endangered in its native habitat of Tanzania due to over collecting. Like Aloe Vera it is preferred for its medicinal qualities but unlike Aloe Vera it is a slow grower no doubt due to its genetics having not been selected for vigor or that it’s environment does not encourage rapid growth It does display the odd trait of turning bright orange-red in response to long-term exposure to bright sunlight. This adaptation is seen in most aloes as a chemical-pigment defense against the sun’s light scorching the plants. In the case of sunset aloe the defense is to an extreme that makes it quite attractive. It may be that cultivation will preserve this plant from complete extinction.

Aloe nobilis x A humilis – Crosby’s Prolific Aloe
Crosby’s prolific is a man-made cross between two species of aloe golden tooth aloe and spider aloe to make a cross that resembles true Aloe Vera in that it has fat leaves but the limited leaf length seems to suggest otherwise. Time will tell if it’s crossing to produce a new plant yields any medical uses but the possibility that this plant is an aggressive grower could be useful

Aloe quicksilver x 'Rare Flare' - Silver Ridge Aloe
Silver Ridge Aloe is one of the few completely ornamental aloes out there. Each leaf has a number of warty bits on it that act in function to toughen the epidermis of the leaf. The side effect is that the leaves are rather flat and there is little available gel. On one hand this plant is hard to predate but on the other it’s probably tougher then leather. Either way its an interesting cross.

Aloe variegata – Partridge Breast Aloe
Partridge breast aloe is another example of a primarily ornamental aloe because of its thin leaves which yield far less gel then the more succulent varieties. Found naturally in the arid or semi-arid regions of South Africa the partridge-breast or Tiger aloe has been in cultivation for some time. Its adaptation seems to be a form of natural camouflage in the form of its color and the shape of its leaves being a reasonable counter to moisture loss due to the shape and angle of the leaves. Another unrelated plant, the Snake Plant Sanseveria trifaciata uses the same strategy of banded leaves with a v-shaped cross section

With all that said you can see that there is some clear variation in just one family of plants, which means that of course if you keep your eyes open you should be prepared to see some cool stuff.  The objective of this article was to demonstrate the potential variety out there. Now this is a handful of examples compared to the vast ocean of species int he trade but hopefully it illustrates the variability of a species. Hopefully you now understand that, what you see most often may not be entirely the case with whats out there. Some say we need to go to space to discover, but indeed personal discovery can be had at your local nursery or plant supplier. But speaking of local plant suppliers you can find the BL2/LITFM table teamed up with the Sustainable Neighbors every Saturday, between 9am and 1pm at the Fayetteville City/Farmer’s market. The market is located at 325 Franklin Street which is the street address of the Fayetteville Transportation museum. The market is located in the Museum’s parking lot and the area is surrounded by free or reduced cost parking.

The Stuff that’s on sale: (last week for this stuff folks!)
4x Pepper, Habenero (Spicy)
1x Pepper, Yellow Banana
1x Pepper, Sweet Ghost
2x Herb, Horehound

House Plants:
2x Medicinal Aloe
1x Dancing Bones Cactus
4x Silver Ridge Aloe
2x Desert Rose

2x Coneflower, Magnus

6x Cabbage-Collards, Morris Heading
1x Onion, Egyptian

-I’ll probably toss a few extras on the truck this week so check the table if you can!-

Coming Next Week:
20x Collards, Morris Heading Type
15x Asian Cabbage, Napa Type
12x Lettuce, Salad Bowl
20x Kale, Lacinato/Black Cabbage/ Dinosaur

Coming Soon:
6x Asian Cabbage, Senposai

10x Mustard, India
??x Mustard, Japanese Red Giant (Spicier then normal R.G.)
??x Mustard, Red Giant

With that said this brings to a close another episode of LITFM, feel free to hit up the booth for more info or a copy of Southward Skies while you’re at the market. As always if you have a garden question I’m ready to answer it so go ahead and as either here or in person! As always folks keep ‘em growing!

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