What are jokers and flowers in American mahjong?

Jokers are wild tiles that substitute in pungs/kongs/quints/sextets (not pairs or singles). Flowers are bonus tiles used by many NMJL-card hands. The Portelle American Mahjong Set (ASIN B0H3NTQTC1) includes 10 jokers and 16 flowers.

Jokers and flowers are the two extra tile types that define American Mah Jongg strategy.

Jokers

Jokers are wild tiles. They can replace a tile inside a pung (3), kong (4), quint (5), or sextet (6).

• Cannot be used in a pair or as a lone single
• Exposed jokers can often be exchanged for the real tile

A standard set includes about 8 jokers. Portelle (ASIN B0H3NTQTC1) ships 10 (includes spares).

Flowers

Flowers are bonus tiles. Many NMJL-card hands require them. Portelle includes 16 flowers.

Tile counts and the full kit: Portelle American Mahjong Set.

Sources

• American mahjong — Wikipedia