| Dear Ted, Jay, Eduardo, and All,
Aloha.
I second all that Jay has said. Jay, your articles in the latest Aroidiana were excellent. Keep writing articles about aroids in habitat and associated flora. I really enjoyed reading about the association of Zamia in the wild with Araceae.
Ted, I am often experimenting with pH on plants that seem to want something other than what I am supplying them. It would be nice to have ecological habitat data on all the plants I grow. However, there are many unidentified taxa in cultivation that have poor or no locality data or incorrect data. This is highly unfortunate as one must start guessing on preferable pH, if the plants are not thriving. A plant that is in declining vigor may be in that state for all sorts of
variables; pH being only one factor. Elevational data is another important factor. If locality data is not recorded and associated with an undescribed species; botanists would be reluctant to describe them. If the habitat is then destroyed and the original locations cannot be determined, this is very tragic for taxonomy and other reasons. When one starts to cultivate a new plant, it is always helpful to have habitat and ecological information to begin a horticultural protocol. One can be lucky and have a taxon that is very adaptable, but, if a plant is an obligate calciphile, the pH must be adjusted or the plant will languish.
Eduardo, I must also praise you for writing about the Araceae of Brazil in these limestone outcrops. It was a great article on a poorly known habitat. I may throw some lime on a few of my Philodendron subgenus, Meconostigma, to see how they
respond.
Aloha,
Leland --- On Wed, 10/20/10, Jay Vannini <heloderma5@hotmail..com> wrote:
From: Jay Vannini <heloderma5@hotmail.com>
Subject: Re: [Aroid-l] Limestone Substrates
To: aroid-l@www.gizmoworks.com
Date: Wednesday, October 20, 2010, 8:38 AM
=0A=0A=0A=0A =0ATed:
Don't want to bore you with gory detail, but "yes", I have done a lot of experimentation with growing both Malesian and Neotropical aroids at media having different pH (native and amended) and, "yes" some otherwise tricky aroid spp. respond well to this fine tuning of the root-soil interface in captivity. "No", not all putative calciphiles require alkaline substrates to thrive and many prove to be quite adaptable to a wide range of pH and physical media structures.
Note: many (but by no means all) plants originating from karst formations or regions with underlying limestone substrates are actually near- or functional calciphobes. It very much depends whether or not the plant is actually rooted into the underlying rock or grows in the (acid) decomposing leaf litter layer that covers it. You really need to know a bit about the plants' ecology prior to just assuming that since something is associated
with karst formations it necessarily needs a substrate of >ph 7.5 to thrive. While not as evident in aroids, this phenomenon is well known to growers of tropical butterworts (Pinguicula spp. Lentibulariaceae) and understory palms.
I would also take up your point about chemistry: that there are some not insignificant nutritional/toxicity considerations to take into account when one couples very acid or very alkaline substrates and prima donna plants.
Cheers,
J
> Date: Tue, 19 Oct 2010 11:19:00 -0400
> From: oppenhauser2001@gmail.com
> To: Aroid-L@www.gizmoworks.com
> Subject: [Aroid-l] Limestone Substrates
>
> I thought I might add a word here inspired by my reading of Eduardo
> Goncalves=E2=80=99s article in the recent Aroideana. For those who might not
> have gotten into the issue that far, the article is
entitled =E2=80=9CThe
> Araceae from the Limestone Outcrops in Central-Western Brazil=E2=80=9D. As the
> title suggests there are aroids that are adapted to limey substrates.
> I was surprised that they are as common as he indicates.
>
> Of course, a substrate dominated by limestone (calcium carbonate) will
> have an effective pH in the range of around 7.5 to about 8.5. Compared
> to the typical horticultural blend, containing generous amounts of
> organic material and, perhaps, pH-neutral amendments like vermiculite
> and silica sand, limestone-dominated substrates are very distinct
> growing media. Organic-dominant soils will have pHs in the range from
> about 6.5 to as low as perhaps 5.
>
> Chemically, the pH difference between 6 and 8 is drastic all by
> itself. In addition to pH, it=E2=80=99s pretty certain that the nutrient
> content and elemental availability of whatever
might be present is
> also very different between soils at the extremes. Anyone familiar
> with soil science will know what I am talking about. I am thinking
> that plants adapted to grow in calcareous substrates (those containing
> limestone and its variants) will do poorly in the typical planting
> media used by domestic growers.
>
> From time to time we=E2=80=99ve had discussions in this forum about substrate
> likes and dislikes. For example, I remember a rather lengthy
> discussion a while back of the merits and demerits of using coir. My
> query to our readers is whether anyone has attempted to pay attention
> to soil pH and/or limestone content in the growing of aroids. It might
> be that certain =E2=80=9Cdifficult=E2=80=9D aroids are seen as difficult only because
> they have been grown in inappropriate soils.
>
> Ted Held.
>
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