Where to Buy Cypress Knee Art in Baton Rouge
The cypresses keep their secrets from the prying investigator.
J. Due east. Rogers,1905
The part of cypress knees has long intrigued botanists. In 1819, François Andre Michaux wrote, "No crusade tin be assigned for their existence," and in 1882 Asa Grey concurred. Nevertheless, throughout the nineteenth century and continuing to the present, botanists have put forth hypotheses virtually the function of these peculiar formations, hypotheses that accept included aeration of the root arrangement, vegetative reproduction, mechanical back up, nutrient accumulation, and sugar storage. The aeration theory has been the most popular and, indeed, is presented without question in some phytology texts, but in fact, no explanation has been generally accepted.1
The genus Taxodium has been present in Northward America since at to the lowest degree the Upper Cretaceous, approximately seventy million years agone, but very little is known about when knees first developed and why. Knees can be found on both varieties at present extant in the Us. Baldcypress (Taxodium distichum var. distichum) is distributed along the coastal plain from southern Delaware to southern Florida, w to southeastern Texas, and inland along the Mississippi Valley equally far north every bit southern Illinois and Indiana. Pondcypress (Taxodium distichum var. imbricarium) has a more than limited distribution, with its northern limit in southeastern Virginia and its range extending due south throughout Florida and west to southeast Louisiana. The two varieties are readily distinguished by their leaf morphology and the orientation of both their leaves and branchlets. While the leaves of baldcypress are needlelike and generally arranged in two rows, those of pondcypress are scalelike and radially distributed effectually the branchlets. Besides, baldcypress branchlets are horizontally oriented, whereas pondcypress branchlets are often ascending. Where they overlap in distribution, withal, at that place is considerable morphological intergradation.ii
Visitors to the cypress swamps of the southeastern United States are frequently intrigued past the bloated bases, or buttresses, of cypresses, and by the woody conical structures—the knees—of varying size constitute around the base of many trees. More than annihilation else, the knees resemble termite mounds, merely are in fact outgrowths of the shallow, horizontal roots of the cypress trees and are not caused by insect activity. Knees are formed on the upper surface of these roots by the vascular cambium, the meristematic layer that produces xylem and phloem, the tissues that transport water and nutrients through the establish. The knees are generally solid, only may get hollow over time due to rotting. In cypress plantations, knees are plant on copse as young every bit twelve years old.three
Cypress knees vary profoundly in size. In 1803, Andrew Ellicot observed knees every bit high as eight to ten anxiety; the tallest on tape is a knee fourteen feet in summit seen on a tree growing along the Suwannee River, which flows through Georgia and Florida.four Many researchers accept agreed that it is boilerplate water depth that determines the peak of knees, and ane observer, Mattoon, reported that the knees on trees growing in softer soils were larger than those produced by trees growing on firmer land.5
In spite of much research and a plethora of hypotheses, exactly what stimulates cypresses to course knees remains, like the knees' function, unknown. In the following, I will review all these hypotheses and the present land of our knowledge nearly cypress knees.
The Aeration Hypothesis
Knees are most often found on the roots of trees growing in wet soil and in relatively shallow water; they are generally absent from trees growing in deeper water and only occasionally on copse growing on land that is dry year-round. In 1934, Herman Kurz and Delzie Demaree, working in Florida, suggested that knees may be caused by the root system existence alternately exposed to h2o and air. In 1956, L. A. Whitford, a researcher working in North Carolina, came to a similar conclusion: "The formation of cypress knees seems … to be a response of the cambium of a root growing in poorly aerated soil or water to chance exposure to the air during the spring or early summertime." Some other indication that aeration may play a role in knee development emerged from research done in 1991 by Fukuji Yamamoto, who observed that the number of knees per tree declined with increasing water depth. The fact that knees have been reported on trees found on land that is dry out twelvemonth-round, of form, throws into question the need for periodic flooding or drying to stimulate knee germination.six
The demand for aeration has been a favorite hypothesis for explaining the office, as well as the formation, of knees. Since all constitute roots need a source of air to conduct out cellular respiration, some researchers have suggested that knees are but a class of pneumatophore, or animate root. Pneumatophores are specialized roots that narrate many woody plants growing in poorly aerated soils, such as in swamps or in the intertidal zone; examples include Avicennia nitida (black mangrove), Sonneratia alba (mangrove apple), and Bruguiera parviflora (small-leafed orange mangrove). Pneumatophores grow either entirely above the level of the water, or in such a way every bit to be exposed only during low tide. They are characterized by the presence of lenticels (porous regions in the bark that permit gas substitution with the atmosphere) and of aerenchyma, the specialized internal tissues that transport gases through many hydrophytic plants.7
The first published proffer that cypress knees may exist a grade of pneumatophores dates from 1848, when Montroville West. Dickenson and Andrew Brownish wrote in the American Journal of Science and Arts that by means of knees "the roots although totally submerged, have a connectedness with the atmosphere." They also suggested that when the knees were inundated, the connection with the atmosphere could be maintained by the bloated base of the tree, sometimes chosen the "canteen buttress": "Such enlargements never fail to rise to the superlative of the highest water level …" In 1887 Nathaniel Shaler conjectured that "[the] function of the knees is in some way connected with the process of aeration of the sap … " with air inbound the knees through newly formed bawl at their apex. He as well observed that trees died when the water rose high plenty to inundate the knees. Two years later, in 1889, some other researcher was fifty-fifty more than categorical: "[the] location and occurrence [of knees] indicate across a doubt that they are for purposes of aerating the plant." In their 1934 newspaper, withal, Kurz and Demaree stated just as categorically that it is "difficult to reconcile the aeration hypothesis with the fact that cypresses of the deeper waters are devoid of knees."8
As early as 1890, Robert H. Lamborn, writing in Garden and Forest, had suggested that tests be conducted to larn whether or not knees were indeed "aerating" the trees' roots. Yet, in spite of all the theorizing, petty was done to test the pneumatophore hypothesis until 1952, when Paul J. Kramer and his colleagues at Duke Academy used modernistic physiological techniques to ascertain the amount of oxygen consumed by knees on living cypresses. They enclosed the knees in airtight containers sealed with a mixture of alkane and beeswax, and used an oxygen analyzer to measure the amount of oxygen consumed over several weeks. The rate of oxygen consumption was really lower than for other plants, leading the researchers to conclude that "the available prove indicates that cypress knees play no of import part equally aerating organs."ix
Anatomical evidence presents another problem for the hypothesis that knees are a form of pneumatophore. Two studies found that knees lack aerenchyma—the spongy tissues in true pneumatophores that transport air from the articulatio genus to the remainder of the root system. In addition, lenticles—the regions of the bark that in pneumatophores allow air to be taken upward from the atmosphere—are also absent from cypress knees.x
The Marsh gas Emission Hypothesis
A less oft heard theory is ane presented by William M. Pulliam in 1992: "Given the possibility that cypress knees provide a conduit to the beneath-ground environment, it was hypothesized in the nowadays report that knees may also evidence methane emissions." Methane is not toxic to plants, only neither is it of use to them.
Pulliam measured full methane emissions from trees in swamps adjoining the Ogeechee River in Georgia, finding rates that averaged 0.nine milligrams per day." His tests showed that cypress knees accounted for a negligible amount of the marsh gas emissions from the swamp-less than one per centum. This methyl hydride is commonly referred to equally "swamp gas." Furthermore, it is quite possible that fifty-fifty this miniscule amount of methyl hydride was being produced by the leaner that are found on the exterior of the knees, rather than beingness vented from the soil through the knees.11
The Vegetative Reproduction Hypothesis
Lamborn, in his 1890 review of what was known near cypress knees at that time, mentioned and and then quickly discarded the idea that cypress knees were organs of vegetative reproduction: "I have … examined hundreds of living 'knees' in southern swamps, and constitute upon them no trace of bud, leaf or sprout …" No one has since revisited this hypothesis.
The Mechanical Support Hypothesis
Buttresses and stilt roots provide mechanical support for a number of tropical copse. Information technology was again Lamborn, in 1890, who outset proposed that knees perform the same function for cypress trees that grow in wet soil: "I became convinced that the about important function of the Cypress knee is to stiffen and strengthen the root, in order that a swell tree may anchor itself safely in a yielding material." Increased support, he believed, allowed cypress to withstand strong winds such every bit those produced by hurricanes. Lamborn suggested that knees located on horizontal roots add stiffness and force to the junction between the horizontal root to which the knees are fastened and the vertical roots that co-operative off direct below the knees. In 1915, Wilbur R. Mattoon, working for the The states Forest Service, concurred with Lamborn, opining that knees were involved in "enlarging and strengthening the basal support" provided by the residuum of the root system. He pointed out that deep roots growing down from the base of the knees provided considerable anchorage for the tree. Both Mattoon and Lamborn premised their hypotheses on the assumption that vertically oriented roots and knees always occur at the aforementioned location on horizontal roots, equally was plainly the case in their observations. However, Clair A. Chocolate-brown and Glen N. Montz institute that cypresses sometimes produce knees at locations other than to a higher place downward-growing roots, and, conversely, that some downward-growing roots do not share a junction with knees on the horizontal roots. And, as with the pneumatophore theory, the absence of knees on the roots of trees growing in deeper water casts incertitude on this hypothesis, since there is no reason to believe that they likewise wouldn't need back up. The hypothesis could be tested empirically in the same way that researchers take used cables and winches to pull down trees in gild to compare the stability of buttressed versus non-buttressed tropical copse-such a test could compare trees with knees to trees that have had their knees removed-but no 1 has all the same washed then.12
The Nutrient Acquisition Hypothesis
Lamborn postulated that another secondary function of cypress knees, along with that of giving mechanical support, was to act as "migrate catchers" that accumulate organic nutrients during periods of water movement. A hundred years later, Hans Kummer and his colleagues at Zurich made a similar supposition about looping cypress roots, which they too chosen knees, afterward studying baldcypress in a Florida cypress dome. (A cypress dome is a group of cypresses growing in a shallow depression where the largest copse are located in the centre and tree pinnacle declines toward the periphery.) They found that the number of looping cypress roots present were highly correlated with the number of dead cypress trees in the dome, but not with the number of live copse. In other words, looping root density increased with an increase in the number of dead cypress stumps. They likewise observed that approximately 98 percent of the youngest looping roots spread over the stumps and penetrated the expressionless forest. Older looping roots were non generally in straight contact with decaying stumps. Direct evidence of food conquering was not obtained, however. Kummer and his colleagues suggested that farther work was needed to determine if "young root loops excerpt nutrients from stumps … [or] … use stumps merely as vertical supports to reach air higher up the h2o table.13
The Carbohydrate Storage Hypothesis
Clair A. Brown in 1984 and again with Montz in 1986 postulated that the primary function of cypress knees is as a storage organ. They reported the presence of "granules"—presumably amyloplasts (organelles that shop starch)—and confirmed the presence of starch by performing iodine tests on the cutting surface of sectioned knees. Even if their hypothesis is authentic, unanswered questions remain virtually the function of knees. Why do cypresses need an auxiliary storage organ when growing nether wet conditions, simply not dry out? Is it possible that cypress roots in general store starch, and that knees are just extensions of these storage areas? Unfortunately, no comparison of the storage capacity of roots and knees has been made to test the hypothesis.14
Commendation: Briand, C. H. 2000. Cypress knees: An indelible enigma. Arnoldia, lx(iv): 19–25.
After almost 2 hundred years of speculation and research, the part or functions of the knees of cypresses remain unclear. Darwin referred to the origin of the flowering plants as an "beastly mystery"; it appears that the function of cypress knees is another.15 The truth may be that cypress knees evolved in response to past environmental pressures that no longer be, in which case their role may exist lost in the depths of fourth dimension. Before we have this decision, however, much further research is needed on this fascinating subject.
Endnotes
1. Julia E. Rogers, The Tree Book (New York, 1905); F A. Michaux, The North American Sylva (Pans, 1819); R. H Lamborn, The knees of the bald cypress; a new theory of their function, Garden and Forest 3 (1890) 21-22; excerpted in Arnoldia sixty(2). xiv-16; J. D. Mauseth, Phytology, 2nd ed. (Philadelphia, 1995).
2. Yard. R. Aulenback and B. A. LePage, Taxodium wallisii sp. nov.: Beginning occurrence of Taxodium from the Upper Cretaceous, International periodical of Found Scientific discipline 159 (1998): 367-390; L. P Wilhite and J. R. Tohver, Taxodium distichum (Fifty.) Rich. Baldcypress, Silvics of North America, ed. R M. Burns and B. H. Honkala (Forest Service, USDA, Washington, D.C.), 563-572; H. S Neufeld, Effects of lite on growth, morphology, and photosynthesis in Baldcypress (Taxodium distichum [L.] Rich ) and Pondcypress (T ascendens Brongn.) seedlings, Message of the Torrey Botanical Society 110 (1983): 43-54; Ibid., Wilhite and Tohver.
iii. W. T. Penfound, Comparative structure of the wood in the "knees," swollen bases, and normal trunks of the tupelo gum (Nyssa aquatica 50.), American journal of Phytology 21 (1934) 623-631; C. A. Brown and One thousand. N. Montz, Baldcypress the tree unique, the wood eternal (Baton Rouge, LA, 1986); D. DenUyl, Some observations on baldheaded cypress yard Indiana, Ecology 42 (1961): 841-843
4. P. J. Kramer. W. S. Riley, and T T. Bannister, Gas substitution of cypress knees, Ecology 33 (1952). 117- 121 ; A. Ellicott, Journal of Andrew Ellicott (Philadelphia, 1803, reprinted Chicago, 1962).
5. Due north. South. Shaler, Notes on the bald cypress, Memoirs of the Museum of Comparative Zoology (Harvard Higher, Cambridge) sixteen (1887): 3-15; W. P Wilson, The production of aerating organs on roots of swamp and other plants, Proceedings of the Academy of Natural Scientific discipline of Philadelphia 41(1889): 67-69; W. R. Mattoon, The southern cypress (USDA Message 272, 1915); H. Kurz and D Demaree, Cypress buttresses and knees in relation to water and air, Ecology xv (1934). 36-41; Chiliad F. Beaven and H. J. Oosting, Pocomoke Swamp: a study of a cypress swamp on the Eastern Shore of Maryland, Bulletin of the Torrey Botanical Club 66 (1939). 367-389; Ibid., Chocolate-brown and Montz; J. L. Kernell and Chiliad. F. Levy, The relationship of bald cypress (Taxodium distichum [L.] Richard) knee height to water depth, Castanea 55 (1990). 217-222.
half dozen. Ibid., Wilson; Kurz and Demaree; DenUyl, Brown and Montz; L. A. Whitford, A theory on the formation of cypress knees, Journal of the Elisha Mitchell Scientific discipline Gild 71 (1956): 80-83; F. Yamamoto, Effects of depth of flooding on growth and beefcake of stems and knee roots of Taxodium distichum, IAWA Bulletin 13 (1992) 93-104.
7. A. D. Bell, Plant Grade (Oxford, 1991).
8. M W Dickeson and A. Brown, On the cypress timber of Mississippi and Louisiana, American Journal of Science and Arts 5 (1848) 15-22; Ibid., Shaler, Wilson; Kurz and Demaree.
9. Ibid, Lamborn; P. J Kramer, W. Southward. Riley, and T. T. Bannister.
x. Ibid., Penfound; Dark-brown and Montz.
xi. West. M. Pulliam, Methane emissions from cypress knees in southeastern floodplain swamp, Oecologia 91 (1992): 126-128.
12. C. Edelin and C. Atger, Stem and root tree compages: Questions for found biomechanics, Blomimetics ii (1994): 253-266; Ibid., Lamborn; Mattoon; Dark-brown and Montz; M J. Crook, A R. Ennos, and J. R. Banks, The part of buttress roots. a comparative study of the anchorage systems of buttressed (Aglaia and Nephelium ramboutan species) and nonbuttressed (Mallotus wrayi) tropical trees, Periodical of Experimental Botany 48 (1997): 1703-1716.
13. Ibid., Lamborn; H. Kummer, et al, Nutritional exploitation of dead trunks: another function of cypress knees (Taxodium distichum) Copse 5 (1991): 122-123; H. Kurz, Cypress domes, Annual Study of Florida State Geological Survey (1933).
14. C. A. Brownish, Morphology and biology of cypress copse, Cypress Swamps, ed. G. C Ewel and H. T. Odum (Gamesmlle, FL, 1984), xvi-24; Ibid., Brown and Montz.
fifteen. D. H. Scott, The Evolution of Plants (New York, NY, 1905).
16. Ibid, Wilson; Bong; Brown & Montz; Penfound; P. B. Tomlinson, The Botany of Mangroves (Cambridge, UK, 1986).
Christopher H. Briand is Acquaintance Professor in the Department of Biological Sciences, Salisbury State University, Salisbury, MD 21801, and producer of the Salisbury Country University Arboretum website (www.ssu edu/arboretum) Thanks are extended to William Grogan, Mark Holland, and Judith Stribling (Salisbury State University) for their assistance and suggestions, and to Joan Rye at the American Journal of Science (Kline Geology Laboratory, Yale University) for providing a copy of the paper by Dickeson and Brown.
Source: https://arboretum.harvard.edu/stories/cypress-knees-an-enduring-enigma/
0 Response to "Where to Buy Cypress Knee Art in Baton Rouge"
Post a Comment