This is inconsistent with regular tall grass, which has an item form for the single block and the double block form.
Linked issues
is duplicated by 10
5 more links
MC-133806
The tall_seagrass block is missing from the menu
Resolved
MC-136166
The item of the tall sea grass is not present in the menu
Resolved
MC-185748
Tall seagrass not in creative inventory
Resolved
MC-226545
Inconsistency issue: Tall Seagrass
Resolved
MC-266918
Missing item variant for Tall Seagrass
Resolved
relates to 1
Comments 3


can confirm in 1.13-pre7
Look at the resolution.
can confirm in 1.13-pre5