| The indumentum of petioles consists of scales and trichomes. |
| Morphological characters including the glandular indumentum and cream flower colour suggest that A. ambiguum is close to A. graniticum. |
| An indumentum was noted in the inflorescence region or in the upper part of the stem. |
| It is variable in size and indumentum of culms, leaves, and panicles. |
| Capitulum bracts are spiny and coated with a dense white arachnoidal indumentum. |
| Herbs, shrubs, subshrubs or little trees, usually with axillary spines, unique indumentum of long, two-celled, barnadesioid hairs on vegetative and reproductive organs. |
