Glossary: H

Species is listed as Historical (not observed for at least 20 years).
The overall shape and bearing of a plant.
The environment in which a plant normally grows.
hair hair
A soft, slender, straight or branched outgrowth of the epidermis, often only one cell thick.
Halictus confusus Halictus confusus
Confusing Sweat Bee, photo USGS Native Bee Inventory and Monitoring Laboratory.
Halictus ligatus Halictus ligatus
Ligated Sweat Bee, photo USGS Native Bee Inventory and Monitoring Laboratory.
Plant adapted to living in saline habitat.
A tree-covered island which rarely floods surrounded by a contrasting wetland ecosystem.
hastate hastate
Leaf base consists of two triangular lobes pointed outward.
haustorium haustorium
The sucker by which a parasitic plant anchors itself on a host plant.
head head
Short, dense inflorescence (synonym: "capitulum").
height height
Vertical distance from the base of a plant at ground-level to the uppermost growing tip.
helical helical
Coiled like a spring.
helix helix
Hemaris diffinis Hemaris diffinis
Snowberry Clearwing Moth, photo ©Mike Boone, .
Hemaris thysbe Hemaris thysbe
Hummingbird Clearwing Moth, photo ©Mike Boone, .
hemiparasite hemiparasite
A parasitic plant that possesses chlorophyll and can photosynthesize but also obtains nutrition from its host plant.
A plant that dies back to the ground at the end of each growing season (non-woody).
Not woody; having the texture of a leaf.
herbage herbage
Stems and leaves (above the ground).
hesperidium hesperidium
A partitioned berry with a leathery, removable rind (such as an orange).
heterophyllous heterophyllous
Producing two or more types of distinct leaves.
hilum hilum
The scar at the point of attachment of a seed.
hirsute hirsute
With stiff, coarse hairs.
hispid hispid
With long, stiff hairs or bristles.
A species not seen for several years.
hollow pith hollow pith
Interior of branchlet has little or no tissue.
holoparasite holoparasite
A parasitic plant that lacks chlorophyll and depends entirely on a host for its nutrition.
homophyllous homophyllous
With leaves and bracts all of similar size.
hood hood
A covering structure formed by the dorsal sepal and erect lateral petals.
Hoplitis truncata Hoplitis truncata
Mason Bee, photo USGS Native Bee Inventory and Monitoring Laboratory.
hydathode hydathode
A structure near a leaf margin that discharges water.
Hyles euphorbiae Hyles euphorbiae
Spurge Hawkmoth, photo ©Norman E. Rees, USDA Agricultural Research Service,
Hyles gallii Hyles gallii
Bedstraw Hawkmoth, photo ©Mike Boone, .
Hyles lineata Hyles lineata
Whitelined Sphinx, photo ©Joseph Berger,
hypanthium hypanthium
A cup- or tube-shaped section of tissue in a flower formed from the fusion of the basal portion of the sepals, petals, and stamens; especially common in many species of rose (Rosa).
hypocotyl hypocotyl
The part of the stem of a young seedling between the radicle (embryonic root) and the cotyledon (embryonic leaf).
hypogynous hypogynous
With a superior ovary that lacks a hypanthium.