Solutions :

3-letter words (1 point): 26

EEK; EEN; EKE; ENE; ERE; ERK; ERR; ERS; ESS; KEN; NEE; NEK; ORE; ORS; ORT; REE; REN; REO; RES; RET; REV; ROE; SEE; SEN; SER; VET.

4-letter words (1 point): 37

DREE; DREK; EKES; ENES; EREV; ERKS; ERRS; KEEN; KERO; KNEE; NEKS; NERD; NERK; NESS; ORTS; REEK; REEN; REES; REKE; RENK; RETS; REVS; RORE; RORT; SEEK; SEEN; SEER; SENE; SERK; SKEE; SKEN; SKER; TREE; TREK; VERS; VERT; VETS.

5-letter words (2 points): 25

DREKS; DRESS; EREVS; ESKER; KERVE; KNEES; NERDS; NERKS; NERTS; NERVE; REEKS; REKES; RETRO; RORTS; SKEEN; SKEER; SKENE; STERE; TEREK; TERSE; TREEN; TREES; TREKS; VERSE; VERTS.

6-letter words (3 points): 10

ENERVE; NERVER; RENKER; RETREE; SKREEN; STREEK; STRENE; TEREKS; TERSER; VERSER.

7-letter words (7 points): 5

RETREES; STREEKS; STRENES; TERREEN; TERRENE.

8-letter word (11 points): 1

TERRENES.