When to neuter. A male dog can be neutered any time after eight weeks of age. A few years ago, most veterinarians advised waiting until puberty hit at about six months, and some still make that recommendation. Talk to your veterinarian about whatâs best for your dog.
The phylum Cycadophyta contains about 140 living species of plants called cycads, with more species present in the fossil record. Cycads have seeds and water-conducting vessels. Cycads belong to a larger group of plants called gymnosperms, which bear seeds in cone-like structures.
Return to phylum directory. The phylum Pterophyta is a group of non-seed plants with a fossil record dating back to the lower Devonian.The phylum consists of about 11,000 living species. Vegetatatively ,the Pterophyta are a diverse group of plants with true leaves, roots and stems.Leaves are macrophylls and, in many families, demonstrate circinate vernation (a pattern of uncoiling of a crozier-like structure due to uneven growth).eturn to phylum directory. The phylum Pterophyta is a group of non-seed plants with a fossil record dating back to the lower Devonian. The phylum consists of about 11,000 living species.