Literally ripping out my hair. I'm watching Ryan Niel's video "Bald Cypress Primer". I'm at the 1:19:40 mark. Ryan is discussing oxygen and water balance for the bald cypress. My forehead is in my hands and I've got my hair in my fists; falling onto my desk. First: That's not a bald cypress (taxodium distichum). That is a pond cypress (taxodium ascendens). Even if we go with the controversial "taxodium distichm var. imbricatum", it's still a pond cypress. Look at the leaves. They're going vertical and they're appressed (thin). Bless his heart. Every time he says "bald cypress" I purse my lips. Second: Bald and pond cypresses form a buttress not because they are swollen with water (as stated in the video), but because they've formed schizogenic intercellular space (aerenchyma) for transport of oxygen. For trees that must withstand periodic flooding, the employment and unemployment cycles for aerenchyma leads to development and redevelopment of that structure. While in continuously flooded trees, the spaces are even larger. Thus, the flooded parts of the plant keep growing the structures required to transport oxygen. "It is likely that well-developed intercellular spaces [aerenchyma] in the phloem of [continuously flooded] bald cypress saplings permitted oxygen transport to the root system..." Megonigal, Day "Effects of Flooding On Root and Shoot Production of Bald Cypress in Large Experimental Enclosures", Ecology, Vol. 73, No. 4 (Aug., 1992), pp. 1182-1193, Ecological Society of America "A layer of spongy tissue characterized by loosely packed parenchyma cells and schizogenic intercellular spaces occurred in the outer 1/4 of the phloem of [periodically flooded] plants but often extended to near the cambial layer in the phloem of [continuously flooded] plants." ibid "Ethylene, a volitile gaseous plant hormone, increases when plant roots are inundated. The enzyme cellulase then increases, causing cell walls to dissolve in the cortex. As these cell walls decompose air channels called aerenchyma develop in the root and stem of some plants and are thought to aid in oxygen transport from aerial portions of the shoot to the flooded root system" Chiplis, Dan J., citing earlier works, "Effect of Flooding on Trunk Diameter in Bald Cypress and Its Application as a Bonsai Technique" Bonsai Clubs International, September/October 1990 "Ethylene is also thought to play a roll in stem hypertrophy. Stem hypertrophy is caused by enlargement of cells and increased intercellular spaces. It is a symptomatic reaction to waterlogging believed to improve the plant's tolerance to flooding." ibid Third: Knees do not exist for gas exchange (as stated in the video). Lenticels do not appear in the developing bark tissue of knees. Their may be some gas exchange, but not enough to say that is their function. "...we conclude that storage of starch is the major function of baldcypress [sic] knees." [emphasis, mine] Brown, Montz "Baldcypress / The Tree Unique, The Wood Eternal" 1986 - Claitor's Publishing Division Think of it as a stem potato (like a yam), but on a tree. It's not a snorkel. It stores food in times of plenty and sends the food down to the roots during hard times. Potatoes grown in sunlight produce an excess amount of sugars. The sugars are combined into complex starch molecules for storage. When the plant needs the energy, the starches are broken back down into sugars. In a bald cypress, the knees are there to feed the roots. I'll be conducting my own multi-year experiment to see if I can grow knees. I have several ideas as to what will influence knee development based partly on some things that I expect will encourage knee development. Unfortunately, I don't have enough room, or funding, to make it a controlled experiment. I'm just going to try a few different things on a few populations of 3 or 4 trees each. I won't be able to definitively say exactly what and why, but I'll be able to say "This is how I did it." (or I'll fail and no knees will form or many trees die. It's going to be exciting!) I'll publish my results (to BonsaiNut and YouTube, of course) in about 10 years.