Well would ya lookit that Welwitschia!

My Welwitschia mirabilis seedlings are coming into their own after only a year.  It’s rather amazing how much growth they have put on.  This is what they look like currently:

Welwitschia, March 2012

Compare this with how the same three plants looked not even a year ago in May of 2011:

Welwitschia, May 2011

Going from right to left in the 2012 picture (left to right in the 2011 picture), here are the current leaf lengths (including the leaf tip dieback):
8.25″ and 8.75″ by .75″ wide
8.75″ and 9″        by .6″ wide
5.25″ and 5″       by .3″ wide
I don’t have an explanation for the one runt.  It’s growing in exactly the same conditions, so I’m assuming it’s a turn of genetics.  On each plant, one leaf is slightly longer than the other.  This could very well be attributed to inaccuracy while measuring.  However, I noticed that all three were on one side of the pot (the one facing us in the first photo).  I’m guess that since the leaves are closer together there, I favored that side when orienting the pot towards the light.  It’s hardly a scientific study, but it looks like light and leaf growth are positively correlated.

Here is the development of the stem/caudex:

stem growth

It’s a poorly-focused photo, but you can see how they are starting to get some girth and become woody.  The two leaf-like growths between the actual leaves are expanding, even starting to brown at the tips.  Supposedly these are truncated axillary buds which continue to expand sideways as the plant grows.  They eventually become the woody “disc” between the leaves of mature plants.  This is where the cones will arise when the plants decide they want to produce strobili (at least 4 years from now).

Here’s a look at the meristematic section where the stem keeps growing new leaf material.  I imagine that this region remains green for the life of the plant since it continually produces new leaf material and must also expand the caudex to accommodate a wider leaf as it grows.

basal meristem

Repotting should be an interesting challenge, especially considering that I have three plants growing in the one pot.  Their surprisingly fibrous root systems are quickly filling up the pot, especially the lower half of the soil, and I imagine untangling them will be difficult.  I have heard conflicting reports about the taproot and repotting.  Some people say it’s crucial to disturb it as little as possible when repotting.  Other sources say that the taproot is really only used for support and anchoring purposes in the wild (since there really isn’t any subterranean water for it to absorb) and consequently the taproot is not that crucial in cultivation.  One paper in particular claims that even removing up to 90% of the root mass during repotting  only causes the plant slight distress.

This is related to the debate about what shape pot Welwitschia prefers.  Traditional wisdom an custom say that a deep pot is required to accommodate the taproot.  However, several botanical institutions growing welwitschias in permanent heated beds have observed that they grow a wide and shallow system of subsurface roots, presumably to take advantage of any moisture which the daily morning fog of its natural habitat may impart to the top layer of soil.  This supports the hypothesis that the taproot is used largely for anchoring and support, rather than as a significant source of water absorption.  Many people successfully grow Welwitschia in standard pots.  The one I am using is only slightly deeper than a standard pot with the same diameter.  The one advantage to a tall, skinny pot is that the long leaves can hang freely down the sides.
When I repot them, I will err on the side of caution, but I’m not anticipating any extreme issues.

Well, I think that about wraps up everything I have to say on Welwitschia for now.  Until next time, happy growing!

Spring Growth Pt. 2

Here is the promised follow-up to last post.  Yes, I know it’s more than “a few days” late, but I doubt there’s anyone following this blog and actively waiting for updates.  These pictures are a month old, so there has been some more growth since then.  I’ll post updates if anything truly exciting happens.  Anyway, here we go!

unknown aroid

Here is an aroid of some sort that a friend gave to me.  If anyone knows what it might be, let me know!  It’s hardy here in NYC (apparently zone 6b), and must be related to jack-in-the-pulpit.  Unfortunately, the inflorescence was slightly past its peak when I took this picture, as evidenced by the browning on the tip of the spadix and top of the spathe.  That aside, this is an utterly ridiculous flower spike.  It’s almost a parody of a normal aroid inflorescence.

For those of you not familiar with this type of inflorescence, here’s how it breaks down.  The long, pointy thing coming out of the top is the spadix.  The part wrapped around it is the spathe, and it covers and protects the actual flowers on the base of the spadix.  In the picture below I’ve pulled of the spadix to reveal the separate clusters of male and female flowers.

the deconstructed inflorescence

This closeup shows how the spadix is actually fused to the spathe on the back, a fact which surprised me.  The male flowers are on top, and the female ones are below.  Aroids usually prevent self-fertalization by releasing pollen when the female flowers are not receptive to pollination.

And now for a completely different biome!  I grew this puppy from seed:

Adansonia digitata

Yes, this is my very own baobab seedling.  The trees are native to Australia, and develop huge, swollen trunks at maturity.  This gives them the colloquial moniker “bottle tree.”  You can see that the base of this one is already swelling, giving the trunk a nice taper, even at just a few months old.  I find this both surprising and pleasing.  I’m not sure why the leaves are so vertical, but for some reason they have moved to a more horizontal position since this picture was taken.  The species name alludes to the fact that the mature foliage of this plant is palmately compound, which is to say that it looks like a hand.  The young leaves, as seen in the picture, are borne singly.  During the winter this will get a dry dormant period to simulate the alternation of wet and dry seasons in its natural habitat.

And here is a true desert gem:

Welwitschia mirabilis

These three (along with one other in a different pot) are my babies.  Also raised from seed which I got from Silverhill Seeds in Cape Town, South Africa.  This plant is one of the famous limit cases of botany, an adaptive extreme.  They live in the Namibian Desert in Namibia and Angola (and maybe a tiny bit in South Africa).  As the picture shows, each plant has two “leaves.”  The bottom pair, however, are the cotelydons, and will fall off within the year.  The top two leaves, amazingly, are the only ones the plant will ever produce.  Rather than grow new leaves, Welwitschia elongates these two leaves continuously from the bottom.  Eventually the desert wind will split them into ribbons that pile up on top of themselves, giving the impression of multiple leaves.  These are technically gymnosperms, which makes them more closely related to pine trees than to anything that flowers.  It’s well worth doing a search for large older plants.  They hypothesize that some of the desert specimens are upwards of 2,000 years old.

To transition back to the tropics, a few posts ago I mentioned a Brassavola that I won at the Manhattan Orchid Society raffle a few months back.  Here, belatedly, is the picture of it.

Brassavola cordata

You can see a fair amount of dead stuff on here.  Like I said, I am rescuing it from the brink of death.  The short left growth is new since it passed into my care.  The right hand leaf that’s cut off by the bottom of the picture is substantially longer, even with half of it dead and removed.  The little guys hitching a ride on the top are Florida strap ferns (Campyloneurum phyllitidis) that I put there to see if they would grow.  So far they haven’t grown, but they haven’t died either.

I know I promised pictures of an orchid flower last post, but I’m going to renege since I think this post  is long enough for now.  Perhaps the flower will get an entire post of its own.  Additionally, keen eyes will have noticed new plants on my plant list (who am I kidding, no one actually noticed that).  These will get their own writeup with pictures ex post haste.

In the meantime, happy growing!