My experience with anachris is that it grows no matter what you do to it (assuming some light and nutrients) Bill is absolutely correct in his suggestion for propogation, but if you want faster/ more plants, the are a couple of other ways to get new plants. if you lay a piece down sideays at the bottom of the tank, it will literraly grow a new plant straight up from every nodule on the stem. I recently hung some upside down in a tank and got a similar result. the plant tried to turn over and grow towards the light, and in the process it sprouted 6 new branches from the main stem (only about 6" long) I cut all of these off and planted them conventionally and they are all growing well. this is in less than 2 weeks from the time I hung it in the tank.
Also you will have roots grow out of the sides of the stems, if allowed to grow they will "reach" for the substrate, and pull the main plant down. at which time multiple new plants will begin growing from the stem that was pulled down.
I started with 6 stems 5 months ago, and have about 50 stems over 10" long now, and multiple short stems growing like weeds. essentially in a few months you will probably be trimming and throwing away large quantities of anachris. just make sure it doesn't go into the local water ways live, it's ability to grow and spread is why it's illegal in several states. All of my plant trimmings get dumped in the garden for fertilizer.
Dave