January 20, 2021 | Last update: December 5, 2021
(see changes at bottom)
Note: Mike Caro has shared his method for recognizing hold ’em boards and threats quickly. If you haven’t read that Poker1 entry, consider visiting it now: → GO THERE
My terrain method teaches hold ’em students to identify threats fast. You’ll be able to instantly see what’s possible in conjunction with the board. It works so effectively that I’ve added a workout to the gym in my forthcoming Mike Caro University Campus software (a years-long project incorporating over 50 research and training tools).
You also can use the lists below to identify threats in Omaha high games.
Three threats, four terrains
The system is simple. There are three possible threats: (1) a full house (and four-of-a-kind); (2) a flush (including a straight flush); and (3) a straight.
There are four terrains, with increasing degrees of vegetation, that broadly define any board: Desert when none of the threats exists; Prairie when one exists; Forest when two of the three exist; and Jungle when all three exist at once.
Often you’ll hear a player say that a board was blank or empty — or use some other similar words. Many times, they’re wrong. There just aren’t that many deserts. Here’s the breakdown.
Total boards: 2,598,960
Deserts: 47,400 (1.82% | 1 in 55 boards | 54-to-1 against)*
Prairies: 1,154,488 (44.42% | 1 in 2.25 boards | 1.25-to-1 against)*
Forests: 1,159,760 (44.62% | 1 in 2.24 boards | 1.24-to-1 against)*
Jungles: 237,312 (9.13% | 1 in 11 boards | 10-to-1 against)*
*Odds and percentages above rounded. Instances exact.
As you can see, only about 1.8 percent of boards are deserts. About 98.2 percent contain a threat of a straight flush, four-of-a-kind, full house, flush, or straight. Even experienced players sometimes overlook these threats when making quick decisions.
In order to be a desert, a board must have no paired ranks, no three or more cards of any suit, and no three ranks close enough to each other that a straight is possible. This means that if you sort the five different ranks high to low, the third card must be more than four notches lower than the first, the fourth card must be more than four notches lower than the second, and the fifth card must be more than four notches lower than the third. Additionally, if an ace is present, then the fourth card must rank six or higher to prevent a five-high straight.
Worst nut hand
Looking at the last board listed below (#79 — Q-8-7-3-2), we can understand why a pair of queens is the lowest-ranking hold ’em starting hand that can ever be guaranteed a win. When matched with that Q‑8‑7‑3‑2, the five-card hand becomes Q-Q-Q-8-7. No lower hand can ever be “the nuts.”
↓ A-K ↓
↓ A-Q ↓
↓ A-J ↓
↓ K-Q ↓
↓ K-J ↓
↓ K-10 ↓
↓ K-9 ↓
↓ K-8 ↓
↓ Q-J ↓
↓ Q-10 ↓
↓ Q-9 ↓
↓ Q-8 ↓
Those are the 79 board types, ordered by ranks, that are deserts when no flush is possible. If your board isn’t listed and you don’t have the best-possible hand or a very strong one, beware of prairies, forests, and jungles!— MC
2021-12-05: Added sentence about applicability to Omaha. Added paragraph reiterating percentage of deserts and stating the percentage of non-desert boards.