ear, ear (grain), head, crest (wave)
穂 centers on the tip or top part of a plant or wave: the grain-bearing ear of a cereal plant, or the foamy crest of a wave. Both senses share the idea of a concentrated, productive endpoint.
穂 combines 禾 (grain plant) with 恵, which likely contributes the sound and may relate to the idea of a concentrated tip or blessing. The exact historical development of the right component is uncertain.
The grain plant 禾 on the left grows a concentrated tip on the right (恵), like the ear of rice or the crest of a wave. Picture a rice plant bowing under the weight of its grain-filled ear.
For スイ, imagine a swaying ear of grain in the breeze: sway -> スイ, and the ear sways gently at the top of the stalk.
ear (of a cereal plant); head; spike
fresh, young ears of rice; lush ears of rice
ear (head) of rice
tip of an ear (of wheat, etc.)
spike
waving heads (of grain)
first ears of rice of the season; first crops of the season; first harvest of the season
appearance of ears of grain
sprouting season (of ears of grain)
harvested grain; harvested rice ears
ceremony fee; money dedicated to the gods when participating in a ceremony
drooping ears (of grain)
the more learned, the more humble; the boughs bearing the most hang lowest
the more learned, the more humble; the boughs bearing the most hang lowest
spikelet; spicule; locusta
scion; cion; (horticultural) graft
spearhead
the Land of Verdant Rice Plants; the Land of Abundant Rice; Japan
ear of a cereal plant
rows of grain thrusting upright