Hardwood is wood (the xylem of the tree) that contains both tracheids and vessels. Softwoods contain only tracheids.
DIAGRAMS: Head Inflorescence
Heartwood is the xylem in the center of the tree that has stopped conducting water and minerals and is storing waste products from the plant. These waste products are of various types. In redwood trees these materials causes the heartwood to turn red. These products help to preserve the wood, particularly in redwoods.
Heartwood can be contrasted with Sapwood, particularly in redwoods, because the heartwood is red and the sapwood is white. The sapwood is the portion of the xylem that is conducting water and minerals and hasn't started storing waste products.
DIAGRAMS: Heartwood / Heartwood
An herb is a plant that has a soft stem and is not woody. Plants that are herbs do not undergo secondary growth.
Herbaceous plants are plants that are herbs with soft, non-woody stems and no secondary growth.
(as in herbs for seasoning)
PHOTOS: Nostoc / Nostoc
Horsetails are a group of tracheophytes that are characterized by stems and rhizomes that have ridges and furrows. In the stem are contained carinal and vallecular canals. The carinal canal is smaller of the two and is associated with the vascular bundle and is opposite the ridges of the stem and rhizome. The vallecular canal is opposite the furrows. Horsetails are in the division Sphenophyta and have only one genus, Equisetum. These plants are typically found in damp to wet habitats.
The hypanthium is found only in dicots and is a fusion of the calyx, corolla, and androecium whorls forming a small cup-shaped structure that surrounds the ovary. Ovaries with a hypanthium are called perigynous ovaries because they have the flower parts (calyx, corolla, and androecium) attached to a hypanthium. The base of the hypanthium is typically attached to the receptacle as is the case with the members of the rose family (Rosaceae) and is therefore said to by hypogynous. The hypanthium can also be epigynous, that is, attached to the top of the ovary, as is the case with the fuschia flower.
Hypogynous ovaries have the flower parts (calyx, corolla, and androecium) attached below the ovary to the receptacle. Hypogynous and superior ovary are synonymous terms.
DIAGRAMS: Hypogynous Ovary