| PS | Paleozoic simple dichotomously branched plants of Europe and eastern Canada including the oldest known vascular land plants |
|---|---|
| PS | any plant of the order Psilophytales: a savannah plant |
| PS | any plant or fossil of the genus Psilophyton |
| PS | whisk ferns |
| PS | falling out of hair |
| PS | small family of lower ferns having nearly naked stems and minute scalelike leaves |
| PS | lower vascular plants having dichotomously branched sporophyte divided into aerial shoot and rhizome and lacking true roots |
| PS | whisk ferns |
| PS | type genus of the Psilotaceae |
| PS | pantropical epiphytic or terrestrial whisk fern with usually dull yellow branches and minute leaves |
| PS | a large bee that resembles the bumblebee but lacks pollen-collecting apparatus and a worker caste |
| PS | coextensive with the order Psittaciformes |