This is a picture of a self-sown giant amaranth (Amaranthus australis) that crossed with one of my ornamental amaranths. All of these plants were similar in size. One in the picture was 19 feet tall. These are much heavier than A. australis plants because the plant is not as hollow. There was very little empty space inside the stem. All of these plants were sterile and produced no seeds. I still have seed from last year that created these hybrids.