male
牡 centers on the male sex of animals, especially livestock. It is used to indicate a male animal, contrasting with female counterparts.
牡 combines 牜 (cow/ox) with 土, which likely originally represented the male organ, to indicate a male animal.
A cow (牜) with a mound of earth (土) beside it, representing the male's strength and solidity. Think of a bull pawing the ground: 牡 is male.
For ボ, imagine a male bull bowing (ボウ) its head before charging. The bowing motion cues ボ, and the bull is male.
oyster; oyster shell
male horse
tree peony (Paeonia suffruticosa); moutan
buck (male deer)
tree peony (Paeonia suffruticosa); winter peony
dahlia (Dahlia pinnata)
Order of the Precious Crown, Peony
tree peony (Paeonia suffruticosa); winter peony
Iwagaki oyster (Crassostrea nippona)
moss-rose purslane (Portulaca grandiflora)
spiny oyster (Saccostrea kegaki)
oysters cooked in the shell
male and female (animals)
kabuki brush (type of powder brush)
variety of Japanese plum
any oriental variety of cherry tree descended from the Oshima cherry
botan shrimp (Pandalus nipponensis)
peony root bark
light crimson; scarlet tinged with purple
Peucedanum japonicum (species of umbellifer with edible leaves)