Poison ivy (and poison oak as well) has three leaves. “Fingers three, turn and flee” is from 1902 and “Leaves three, quickly flee” is from 1904. The rhyme “leaflets three, let it be” has been cited in print since at least 1907.
“Leaves of three, let it be!” was cited in print in 1959 and “Leaves of three, let them be” was cited in print in 1977. However, the rhyme minimizes the danger of other plants; poison sumac has 7—13 leaflets.
Similar poison ivy rhymes include “Leaves of five, let it thrive,” “Berries white, a poisonous sight,” “Hairy vine, no friend of mine” and “Raggy rope, don’t be a dope.”
Wiktionary: leaves of three, let it be
leaves of three, let it be
1.Don’t touch a plant with a cluster of three leaves because it might be poison ivy.
Wikipedia: Toxicodendron radicans
Toxicodendron radicans, commonly known as poison ivy (older synonyms are Rhus toxicodendron and Rhus radicans), is a poisonous North American plant that is well known for its production of urushiol, a clear liquid compound found within the sap of the plant that causes an itching, irritation and sometimes painful rash in most people who touch it. The plant is not a true ivy (Hedera).
Various mnemonic rhymes describe the characteristic appearance of poison ivy:
1."Leaflets three; let it be” is the best known and most useful cautionary rhyme. It applies to poison oak, as well as to poison ivy.
2."Hairy vine, no friend of mine.”
3."Longer middle stem; stay away from them.” This refers to the middle leaflet having a visibly longer stem than the two side leaflets and is a key to differentiating it from the similar-looking Rhus aromatica (fragrant sumac).
4."Raggy rope, don’t be a dope!” Poison ivy vines on trees have a furry “raggy” appearance. This rhyme warns tree climbers to be wary. Old, mature vines on tree trunks can be quite large and long, with the recognizable leaves obscured among the higher foliage of the tree.
5."One, two, three? Don’t touch me.”
6."Berries white, run in fright” and “Berries white, danger in sight.”
Stories of Woods and Fields
By Elizabeth Virginia Brown
Yonkers-on-Hudson, NY: World Book Company
“All you have to do is look at the leaves in the summer and the berries in the fall,” said Fred. “If the leaves have five fingers, you may safely put your hand on them, for they belong to the friendly creeper; but if they have but three fingers, you must not touch them, for they are poison ivy. In the fall, the berries of the Virginia creeper are red, while those of the poison ivy are white.
“You can always tell the ivy from the creeper if you remember, --
Turn and flee!
Let them thrive!
Have no dread!’”
Google News Archive
27 July 1904, Pittsburg (PA) Press, “Poison Ivy,” pg. 4, col. 5:
Poison ivy has three leaflets, and Virginia creeper has five. The former has white berries, the latter purple.
There is a little jingle which I remember having at some time read, which, concisely, if not very poetically, explains these differences, and which, if committed to memory, will always serve to distinguish the poisonous and non-poisonous sumacs:
Have no dread;
Leaves three, with berries red,
Fragrant sumac, have no dread.”
October 1907, Kindergarten Review, “Nature Notes,” pg. 122, col. 2:
The poison ivy, with its leaves of three leaflets, becomes noticeable because if its many whitish berry-like fruits. The Virginia creeper, with which the poison ivy is sometimes confused, has five leaflets to a leaf and a small black fruit. Remember always, “Leaflets three, let it be.”
11 September 1920, Elkhart (IN) Truth, “Tell How to Distinguish Poison from Harmless Ivy,” pg. 6, col. 1:
The homely saying “leaflets three, let it be” may cause unjust suspicion of some innocent and harmless plants, but it offers a deal of good advice to those who are unacquainted with poison ivy.
25 August 1921, Jasper (MO) News, pg. 9, col. 2:
Let It Be!”
23 May 1959, Cleveland (OH) Plain Dealer, “Aerosol Kills Poison Ivy” by Irma Bartell, pg. 31, col. 2:
“Leaves of three, let it be!”
27 May 1965, The Oregonian (Portland, OR), sec. 2, pg. 16, col. 7 photo caption:
SUNNYSIDE PRINCIPAL Ben Schellenberg shows students how to identify three-leafed poison ivy, and tells them how to remember it.."Leaves of Three—Let It Be.” he explains that plant has three leaves to each stem.
Google News Archive
26 June 1968, Observer-Reporter (Washington, PA), sec. A, pg. 6, col. 3:
Leaves Of Three, Let It Be
By EDNA HALLIDAY
Distributed by Central Press Association
DON’T GET acquainted with poison ivy on a picnic.
20 July 1977, New York (NY) Times, “Personal Health; Learn to Recognize and Avoid Poison Ivy, Oak and Sumac” by Jane E. Brady, Living sec., pg. 51:
“Leaves of three, let them be . . .” The familiar warning refers to the one fixed characteristic of poison ivy and poison oak: the fact that each leaf always consists of three leaflets.
New York (NY) Times
GARDENING;’Leaves of Three, Let Them Be’ in Ivy Time
By JOAN LEE FAUST
Published: July 7, 1996
The old adage of “leaves of three, let them be” is a good rule to follow. The plants start out simply enough as cute little seedlings, just an innocent looking neat cluster of shiny leaves. At this stage, the little things can be ruthlessly, if carefully, pulled out. Be sure hands are well gloved, but remember that the gloved hands have been used to pull up poison ivy and even if the nose itches, don’t scratch.
Dangerous Wildlife in the Mid-Atlantic:
A Guide to Safe Encounters at Home and in the Wild
By F. Lynne Bachleda
Birmingham, AL: Menasha Ridge Press
The famous “leaves of three, let it be” is good rule to follow, but some plants don’t always play by the rules. Poison sumac, tor example, has 7—13 leaflets.
New York (NY) Times
Avoiding the Dangers Down in the Garden
By JANE E. BRODY
Published: July 17, 2007
“Leaves of three, let them be.” No doubt you’ve heard this warning about poison ivy, a weedy plant that each year causes more than 350,000 reported cases of human contact dermatitis, and probably many thousands more unreported cases.
The Poison Oak and Poison Ivy Survival Guide
By Sandra J. Baker
Medford, OR: Coleman Creek Press
(leaves changed to leaflets for botanical accuracy)
Leaflets three, let it be; leaflets five, let it thrive.
Berries red, have no dread; berries white, a poisonous sight.
Hairy vine, no friend of mine. (poison ivy vines)
Raggy rope, don’t be a dope. (poison ivy vines)
Red leaves in the spring, it’s a dangerous thing.
Trenton (MO) Republican-Times
June 21st, 2013
Leaves Of Three Are Not for Me
By Jeff Berti
Poison ivy. The name strikes fear in the hearts of many. But don’t let this plant keep you from enjoying the outdoors.
Poison ivy grows just about anywhere, including wet or dry woods, fields, fencerows, and gravel bars. It comes in many shapes and sizes, but usually is a vine or low shrub. The leaves typically have a glossy surface, and occur at the end of long leaf stems. In the fall, the leaves turn brilliant shades of red, orange and yellow. Remembering this jingle may help you identify the plant: “Leaves of three, let it be. Berries white, a poisonous sight.”