I think there is no definitive answer to the cause of them. Although one or two people admitting to make a few with a plank does not mean all are fake. But to the cause who knows.
PLANT ABNORMALITIES
The physical changes (listed below) documented in crop circle plants by Michigan biophysicist W.C. Levengood have been determined by evaluating hundreds of sample plants -- both downed and standing -- taken from inside the overall perimeter of each formation against hundreds of control plants taken at varying distances outside each formation, in several directions. More than 250 individual crop formations from multiple countries, over a 10-year period were examined in-depth. Although many of the formations studied were relatively "simple" in overall design and/or relatively "small" in overall size (primarily because of BLT's financial and/or personnel limitations, particularly in Europe), many larger and more "complex" formations -- those whose overall design included intricate geometric shapes with multiple design elements of varying sizes -- are represented here.
Many of the formations occurred in European countries and, in those cases, the plants were dried-down in open air for 4-6 weeks prior to shipping to the U.S. Some of the U.S. and Canadian formations were shipped while still green. The physical changes found in these crop circle plants, outlined below, have all been determined to be statistically significant at the 95% level of confidence:
1.
On the microscopic level, abnormal enlargement of cell wall pits in bract tissue (a thin membrane which surrounds the seed- head and through which nutrients pass to the developing seed) were found. This examination utilizes the optical microscope and is quite time-consuming and, although useful in the early, exploratory stages of the research, was replaced when equally reliable criteria were subsequently discovered.
2a.
Enlarged (both laterally and longitudinally) plant stem nodes - the fibrous "knucle-like" protuberances found spaced along the plant stem beneath the seed-head, technically called "pulvini." Although these nodes are sometimes enlarged both laterally (they are "fatter") and longitudinally (they are "stretched"), extensive laboratory work has determined that it is the node elongation (the stretching) that is a permanent effect caused by the formation energies - and so this is the parameter now used.
Apical Node Elongation
2b.
In some crop formations the energy system involved is intense enough to cause bending of this apical (top) node (although pronounced node bending is much more commonly found at the lower nodes on the plant stem). In a few cases we have found severe apical node bending in conjunction with marked stretching of the node. As the example, below, illustrates the node elongation in such cases is clearly in addition to that caused by the bending of the node tissues.
Sample plants with apical node elongation and extreme bending, in wheat from a Maryland, USA crop formation.
Apical nodes in control plants from the same field, taken a distance away from the crop formation.
Plant Elongation
Four plants on left (from an Italian crop circle) show apical node elongation & slight bending. Two apical nodes on right are from controls.
3a.
Marked bending of the plant stem nodes which can occur at all of the nodes in some cases, is most often observed in the 2nd, 3rd and 4th nodes down toward the bottom of the stalks. It does occasionally occur in the first, or apical node beneath the seed-head (see above). Usually this bending (if it is determined to be significant after ruling out natural plant recovery processes) is in the range of 45-90 degrees and considerable care must be taken to not confuse this node bending with two well-known plant recovery processes:
(1) phototropism (the plant's natural tendency to reorient itself to sunlight) and;
(2) gravitropism (the plant's natural tendency to reorient itself to the earth's gravitational field).
NODE BENDING, which may (depending on the age of the crop when formation occurred & time elapsed since then) or may not be indicative of the genuine phenomenon.
Depending upon the growth-stage of the plant at the time it is downed (whether it is young or old) and the species of crop involved, these natural recovery processes - phototropism and gravitropism - begin to take effect within days. Therefore node bending can only be understood as significant when it is known how old the affected crop was at the time the crop circle occurred and, particularly, how many days have elapsed since then. [Young barley, for instance, begins recovery to the up-right position almost immediately and will show significant node bending within a week; young wheat tends to recover slightly more slowly. And mature crop may not reorient itself at all, depending on the amount of vigor inherent in the plants.] But when crop circles are known to have formed during a specific time period and are found within 24-48 hrs., and significant node bending (40° +) is observed, this is an effect that can be attributed to the causative energy system. In some cases canola (rape-seed) plants have been observed to be bent at a full 180°.
4.
Expulsion cavities (holes blown out at the plant stem nodes), usually found in the 2nd node beneath the seed-head, but in recent years discovered also in the 3rd and 4th nodes all the way down the plant stem. A darkening of the stem node, particularly when expulsion cavities are present, is usually the result of the growth of an opportunistic fungus (Ustilago tritici) which quickly forms on the exudate released from inside the plant stem.
expulsion cavity
Typical expulsion cavity found when crop circles occur in young wheat, oats & barley. These holes are not always present in "real" circles and occur usually in the 2nd or 3rd nodes down from the seed-head.
Expulsion cavities in older, mature plants can also look like this example, in mature wheat.
Expulsion cavities in older, mature barley plants.
5.
Stunted, malformed seeds and germination effects. There are four basic changes to the seeds and germination capability in crop circle plants documented so far. These radically different reproductive effects depend upon the species of crop involved, the growth phase of the plants at the time the crop circle occurs, and the composition and intensity level of the energy system involved (which appears to differ slightly within each event as well as from event to event):
(a) If the crop circle occurs prior to anthesis (the flowering of the plant) and the development of the seed, the somatic (non-reproductive) tissue of the plant will continue to develop normally -- but seed development ceases or is impaired. Normally-formed glumes have been found which are totally devoid of seeds.
SEED-HEADS, WHEAT
Crop circle seed-head (right) has no seeds, due to destruction of plant's reproductive capacity. Found only when crop circles occur in very immature plants.
(b) When crop circles occur at a slightly later growth stage, in young crop where the seed is still forming, the developing embryo fails to grow normally. These seeds will be visually stunted (smaller), will weigh less than their controls, and will exhibit reduced or repressed germination. Here, the reproductive capacity of the plant has been compromised.
STUNTED & DEHYDRATED
MAIZE SEEDS (on right).
These occur when embryos are already formed, or partially formed,
when crop circle occurs.
CONTROL MAIZE SEEDLINGS AT 7 DAYS
FORMATION MAIZE SEEDLINGS AT 7 DAYS
Showing reduced seedling growth-rate, which typically occurs if crop circles form in plants which are at an intermediate growth-stage.
(c) When crop circles occur in more mature plants, where the embryo is fully formed or nearly so, the seeds will again be visually stunted and will weigh less than normal, but the effects on reproduction vary. One effect observed has been an alteration in normal growth-habit of the developing seedlings: in species which have a normal variability of growth at particular stages, this variability has been lost -- with the result being that all of the germinating seeds exhibit synchronized growth.
CONTROL SEEDLINGS, 12-DAY WHEAT
Showing normal variation of growth-rate (height)
for this particular species at this stage of development.
FORMATION SEEDLINGS, 12-DAY WHEAT
Showing induced synchronization of growth.