I have been working on several tropical inspired projects lately, designing lots of cacti, and this brooch is a result of the first tries. It is really small - about 6 cm long.
Yarn and hook: sport yarn and a 1.9mm hook.
Crochet terms (US terminology): chain (ch), slip stitch (sl st.), single crochet (sc), half double crochet (hdc).
Other: sewing and tapestry needle and sewing thread, brooch pin.
Foundation and row 1: Ch12 and hdc3 in 2nd st from hook, then hdc1 across in the next 10 sts. Ch1 and hdc1 in next 10 sts.
Row 2: Sl st in the next and continue slip stitching around. When you come to the 5th st on the other side, ch5 (for the small cactus segment) and hdc2 in the last st from hook, sk 2, sl st in the 3rd st and 2 last sts to finish the round. Leave a long tail, you'll use to sew the pin at the back. Thread it through the tapestry needle and insert it so it comes at the back. Position the pin and use the tail to fasten it.
Ch4 and hdc1 in 1st st. Repeat this once more, then sl st in the very 1st st to close. Work tails.
Flower pot pattern
Foundation and row 1: ch4, turn work and sc1 in all (3). ch1 and turn work.
Row 2: sc1 in all (3). ch1 and turn work.
Row 3: Sc1 in 2 sts, sc2 in last (4) . ch1 and turn work.
Row 4: Sc1 in all (4). ch1 and turn work.
Row 5: Sc2 in first 3 st, sc1 in next two, and finally sc2 in last st(6).
Thread a sewing needle and sew the flower on top of the cactus (or on the segment). Sew the pot over the lower part of the cactus, and you are done.
Hope you have fun!