vine, tendril, influence, connections, good offices, spread, sprawl, thrive, rampant, powerful
蔓 centers on the idea of something that extends and spreads like a vine: a physical tendril, sprawling growth, or figurative influence and connections that reach out and thrive rampantly.
蔓 combines 艹 (grass/plant) with 曼, which likely contributes both sound and the idea of extending or spreading. The character originally referred to creeping plants and later gained figurative senses of spreading influence.
The grass radical 艹 sits above 曼, which looks like a net spreading out. Picture a vine with tendrils creeping over a trellis, spreading its influence everywhere.
For マン, imagine a man tangled in sprawling vines: man -> マン, and the vines spread rampantly around him.
spread (e.g. of a disease); rampancy; infestation; proliferation; being widespread
to become overgrown; to grow thick
vine; bine; tendril; runner
pitcher plant
Actinostemma lobatum (plant of the family Cucurbitaceae)
connections; contacts; influence
basket star (any brittlestar of family Euryalina); basket fish
common clubmoss (Lycopodium clavatum); stag's-horn clubmoss; running clubmoss; ground pine
black gram (Vigna mungo); black lentil
gourd vine
like begets like; the apple doesn't fall far from the tree; eggplants don't grow on gourd vines
jiaogulan (species of herbaceous vine; Gynostemma pentaphyllum)
Chinese asparagus (Asparagus cochinchinensis)
deodeok (Codonopsis lanceolata); todok
zebra sole (Zebrias zebrinus)
coiled spring; coil spring; helical spring
vine-like; climbing; creeping
creeper (plant that grows along the ground, etc. similar to a vine)
bigleaf periwinkle (Vinca major); greater periwinkle
Celastrus orbiculatus