HACKELIA (Family: Boraginaceae)

Hackelia americana (A. Gray) Fernald - . 2n = 24.

Calcareous rocky woodlands or talus, roadsides. [H. deflexa (Wahlenberg) Opiz var. americana (A. Gray) Fernald & I.M. Johnston]

Hackelia virginiana (Linnaeus) I.M. Johnston - . 2n = 24.

Rich, open, deciduous woodlands and thickets, roadsides.

HALENIA (Family: Gentianaceae)

Halenia deflexa (Smith) Grisebach subsp. deflexa - Spurred Gentian. 2n = 22.

Moist banks, wet woods, fields, roadsides.

HALERPESTES (Family: Ranunculaceae)

Halerpestes cymbalaria (Pursh) Greene - Seaside Crowfoot. 2n = 16.

Salt marshes, sea beaches. [Ranunculus cymbalaria Pursh]

HALESIA (Family: Styracaceae)

HALESIA CAROLINA Linnaeus - Carolina Silverbell. 2n = 24.

Moist, deciduous woods, roadsides. From farther south and west. [H. tetraptera J. Ellis]

HAMAMELIS (Family: Hamamelidaceae)

Hamamelis virginiana Linnaeus - Witch-hazel. 2n = 24.

Rich, moist woods, thickets. [H. virginiana var. parvifolia Nuttall]

HARRIMANELLA (Family: Ericaceae)

Harrimanella hypnoides (Linnaeus) Coville - Moss-plant. 2n = 32, 48.

Mossy alpine or subalpine areas. [Cassiope hypnoides (Linnaeus) D. Don]

HEDEOMA (Family: Lamiaceae)

HEDEOMA HISPIDA Pursh - . 2n = 18, 38.

Dry fields, calcareous ledges, roadsides. From farther west and south.

Hedeoma pulegioides (Linnaeus) Persoon - American False Pennyroyal. 2n = 38.

Dry fields, ledges, roadsides.

HEDERA (Family: Araliaceae)

HEDERA HELIX Linnaeus - English Ivy. 2n = 48, (96).

Roadsides, disturbed woodlands. From Eurasia, northwestern Africa.

HEDYSARUM (Family: Fabaceae)

Hedysarum alpinum Linnaeus - . 2n = 14, (16).

Calcareous river-shores, ledges. [H. alpinum var. americanum Michaux ex Pursh]

HELANTHIUM (Family: Alismataceae)

Helanthium tenellum (Martius ex Schultes (son)) Britton - . 2n = 22, (33).

Sandy shores of streams and lakes. [Echinodorus parvulus Engelmann; E. tenellus (Martius ex Schultes (son)) Buchenau]   GH herbarium image

HELENIUM (Family: Asteraceae)

HELENIUM AMARUM (Rafinesque) H. Rock var. AMARUM - Yellowdicks. 2n = 30.

Waste places, railroads. From farther south. [H. TENUIFOLIUM Nuttall]

Helenium autumnale Linnaeus - Common Sneezeweed. 2n = (32), 34, (36).

Shores, meadows. [H. autumnale var. canaliculatum (Lamarck) Torrey & A. Gray; H. autumnale var. parviflorum (Nuttall) Fernald]

HELENIUM FLEXUOSUM Rafinesque - Purplehead Sneezeweed. 2n = 28.

Meadows, shores, fields. From farther south. [H. NUDIFLORUM Nuttall]

HELIANTHUS (Family: Asteraceae)

HELIANTHUS ANNUUS Linnaeus - Common Sunflower. 2n = 34, (68).

Waste places, roadsides. From farther west.

HELIANTHUS DEBILIS Nuttall subsp. CUCUMERIFOLIUS (Torrey & A. Gray) Heiser - 2n = 34.

Waste places, fields. From farther south.

Helianthus decapetalus Linnaeus - 2n = 34, 68, (102).

Open woods, thickets, often moist soil near streams, roadsides. [H. trachelifolius Miller]

Helianthus divaricatus Linnaeus - Woodland Sunflower. 2n = 34.

Dry, thickets, woods, and openings, roadsides. [H. divaricatus var. angustifolius Kuntze]

Helianthus giganteus Linnaeus - 2n = 34.

Dry fields, salt marsh borders, usually wet, open sites.

HELIANTHUS GROSSESERRATUS M. Martens - 2n = 34.

Roadsides, sandy fields, rich thickets. From farther west.

HELIANTHUS MAXIMILIANI Schrader - 2n = 34.

Waste places, fields. From farther west. [H. dalyi Britton]

HELIANTHUS MOLLIS Lamarck - Ashy Sunflower. 2n = 30, 34.

Dry, sandy fields, roadsides, waste places. From farther south and west.

HELIANTHUS PAUCIFLORUS Nuttall subsp. PAUCIFLORUS - 2n = (68), 102.

Dry, sandy fields, waste places. From farther west. [H. LAETIFLORUS Persoon var. RIGIDUS (Cassini) Fernald]

HELIANTHUS PAUCIFLORUS Nuttall subsp. SUBRHOMBOIDEUS (Rydberg) O. Spring & E.E. Schilling - 2n = 102.

Roadsides, waste places. From farther west. [H. LAETIFLORUS Persoon var. SUBRHOMBOIDEUS (Rydberg) Fernald]

HELIANTHUS PETIOLARIS Nuttall subsp. PETIOLARIS - Prairie Sunflower. 2n = 34.

Dry roadsides, waste places. From farther west.

Helianthus strumosus Linnaeus - 2n = 68.

Thickets, open woods, clearings, roadsides.

HELIANTHUS TUBEROSUS Linnaeus - Jerusalem Artichoke. 2n = 102.

Waste places, roadsides, fields. From farther west and south. [H. TUBEROSUS var. SUBCANESCENS A. Gray]

Helianthus hybrids

Helianthus X ambiguus (Torrey & A. Gray) Britton (pro species) - .

[H. divaricatus Linnaeus X H. giganteus Linnaeus]

HELIANTHUS X DIVARISERRATUS R.W. Long - .

[H. divaricatus Linnaeus X H. GROSSESERRATUS M. Martens]

HELIANTHUS X DORONICOIDES Lamarck (pro species) - .

[H. giganteus Linnaeus X H. MOLLIS Lamarck]

HELIANTHUS X INTERMEDIUS R.W. Long - .

[H. GROSSESERRATUS M. Martens X H. MAXIMILIANI Schrader]

HELIANTHUS X KELLERMANII Britton (pro species) - .

[H. GROSSESERRATUS M. Martens X H. SALICIFOLIUS A. Dietrich]

HELIANTHUS X LAETIFLORUS Persoon (pro species) - .

[H. PAUCIFLORUS Nuttall X H. TUBEROSUS Linnaeus]

HELIANTHUS X LUXURIANS E. Watson (pro species) - .

[H. giganteus Linnaeus X H. GROSSESERRATUS M. Martens]

HELIOMERIS (Family: Asteraceae)

HELIOMERIS MULTIFLORA Nuttall var. MULTIFLORA - 2n = 16.

Wool waste. From farther west.

HELIOPSIS (Family: Asteraceae)

HELIOPSIS HELIANTHOIDES (Linnaeus) Sweet var. HELIANTHOIDES - False Sunflower. 2n = 28.

Fields, waste places, thickets. From farther west and south.

HELIOPSIS HELIANTHOIDES (Linnaeus) Sweet var. SCABRA (Dunal) Fernald - 2n = 28.

Fields, waste places, thickets. From farther west.

HELIOTROPIUM (Family: Heliotropiaceae)

HELIOTROPIUM AMPLEXICAULE Vahl - . 2n = 26, 28.

Waste places. From South America.

HELIOTROPIUM CURASSAVICUM Linnaeus var. CURASSAVICUM - Seaside Heliotrope. 2n = (24), 26, 28, 52.

Sandy, saline soil. From southeastern North America, Central and South America.

HELIOTROPIUM EUROPAEUM Linnaeus - European Heliotrope. 2n = (24), 32, 48.

Waste places, wool waste. From Eurasia, northern Africa, Australia.

HELIOTROPIUM INDICUM Linnaeus - Turnsole. 2n = 22, 24, (64).

Waste places. From South America.

HELMINTHOTHECA (Family: Asteraceae)

HELMINTHOTHECA ECHIOIDES (Linnaeus) Holub - Oxtongue. 2n = 10.

Fields, waste places, roadsides. From Eurasia, northern Africa. [PICRIS ECHIOIDES Linnaeus]

HEMEROCALLIS (Family: Xanthorrhoeaceae)

HEMEROCALLIS FULVA (Linnaeus) Linnaeus - Orange Day-lily. 2n = 22, 33, (36), (44).

Roadsides, waste places. From Asia.

HEMEROCALLIS LILIOASPHODELUS Linnaeus - Yellow Day-lily. 2n = 22.

Roadsides, waste places. From Asia. [H. FLAVA (Linnaeus) Linnaeus]

HEPATICA (Family: Ranunculaceae)

Hepatica acutiloba de Candolle - Sharp-lobed Hepatica. 2n = 14.

Rich, often calcareous, woods. [H. nobilis Miller var. acuta (Pursh) Steyermark; Anemone acutiloba (de Candolle) G. Lawson]

Hepatica americana (de Candolle) Ker Gawler - Round-lobed Hepatica. 2n = 14.

Rich, dry, open woods. [H. nobilis Miller var. obtusa (Pursh) Steyermark; Anemone americana (de Candolle) H. Hara]

HERACLEUM (Family: Apiaceae)

HERACLEUM MANTEGAZZIANUM Sommier & Levier - Giant Hogweed. 2n = 22.

Roadsides, woodland clearings, field and woodland margins. From the Caucasus region.

Heracleum sphondylium Linnaeus subsp. montanum (Schleicher ex Gaudin) Briquet - Cow-parsnip. 2n = 22.

Moist, rich ground. [H. lanatum Michaux; H. maximum W. Bartram]

HERACLEUM SPHONDYLIUM Linnaeus subsp. SIBIRICUM (Linnaeus) Simonkai - Hogweed. 2n = 22.

Fields, roadsides, waste areas. From Eurasia. [H. SPHONDYLIUM var. ANGUSTIFOLIUM Jacquin]

HERNIARIA (Family: Caryophyllaceae)

HERNIARIA GLABRA Linnaeus - Green-carpet. 2n = 18, (36).

Roadsides, waste places. From Eurasia.

HERNIARIA HIRSUTA Linnaeus var. HIRSUTA - Hairy Rupturewort. 2n = (18), 36.

Roadsides, sandy flats. From Europe, southwestern Asia, northern Africa.

HESPERIS (Family: Brassicaceae)

HESPERIS MATRONALIS Linnaeus - Dame’s-rocket. 2n = 14, (16), 24, 28, (32).

Roadsides, waste places, thickets. From Eurasia, northern Africa.

HETERANTHERA (Family: Pontederiaceae)

Heteranthera dubia (Jacquin) MacMillan - Water Stargrass. 2n = 30.

Shallow, quiet, basic water. [Zosterella dubia (Jacquin) Small]

Heteranthera reniformis Ruiz & Pavón - . 2n = 24, 48.

Muddy river shores (in mud or floating in shallow water).

HETEROSPERMA (Family: Asteraceae)

HETEROSPERMA PINNATUM Cavanilles - Wingpetal. 2n = 50.

Wool waste. From farther west.

HETEROTHECA (Family: Asteraceae)

HETEROTHECA SUBAXILLARIS (Lamarck) Britton & Rusby subsp. LATIFOLIA (Buckley) Semple - . 2n = 18.

Roadsides. From farther south.

HEUCHERA (Family: Saxifragaceae)

Heuchera americana Linnaeus var. americana - Rock-geranium. 2n = 14.

Rich, wet woods.

HIBISCUS (Family: Malvaceae)

Hibiscus moscheutos Linnaeus subsp. moscheutos - Swamp Rose-mallow. 2n = 38.

Marshy river borders, brackish, freshwater, and salt marshes. [H. palustris Linnaeus]

HIBISCUS SYRIACUS Linnaeus - Rose-of-Sharon. 2n = 40, 80, 88.

Woodland margins, roadsides, thickets. From China, Taiwan.

HIBISCUS TRIONUM Linnaeus - Flower-of-an-hour. 2n = (28), 56.

Railroads, roadsides, waste places. From Eurasia, Africa.

HIERACIUM (Family: Asteraceae)

HIERACIUM AURANTIACUM Linnaeus - Devil’s Paintbrush. 2n = (30), 36, (45), (54), (63).

Fields, clearings, roadsides. From Europe.

HIERACIUM CAESPITOSUM Dumortier - Yellow Fox-and-cubs. 2n = 18, 36, 45, (72).

Fields, clearings, roadsides. From Europe. [H. PRATENSE Tausch]

HIERACIUM FLAGELLARE Willdenow - 2n = 45, 54.

Waste places, roadsides, fields. From Europe.

Hieracium gronovii Linnaeus - 2n = 18.

Dry fields, open pine or pine-oak woods, dry openings, roadsides.

HIERACIUM LACHENALII Suter - European Hawkweed. 2n = 27, (36).

Roadsides, thickets, openings in woods. From Europe. [H. VULGATUM Fries]

HIERACIUM MACULATUM Schrank - 2n = 27.

Calcareous till. From Europe.

Hieracium marianum Willdenow - . 2n = ?

Dry woods and woodland margins, dry banks, roadsides. [Note: This is thought by some to be a hybrid between H. venosum Linnaeus and H. scabrum Michaux or H. gronovii Linnaeus.]

HIERACIUM MURORUM Linnaeus - Golden Lungwort. 2n = 27, (36).

Roadsides, fields, thickets, openings in woods. From Eurasia.

Hieracium paniculatum Linnaeus - Allegheny Hawkweed. 2n = 18.

Dry, often rocky, open woods, roadsides.

HIERACIUM PILOSELLA Linnaeus - Mouse-ear Hawkweed. 2n = (18), 36, 45, 54, 63, (72), (81), (90).

Dry, open soil, fields, roadsides. From Eurasia. [H. PILOSELLA var. NIVEUM Müller Argoviensis]

HIERACIUM PILOSELLOIDES Villars - Glaucous King Devil. 2n = 18, 27, 36, 45, 54.

Fields, roadsides, clearings. From Eurasia. [H. FLORENTINUM Allioni]

HIERACIUM PRAEALTUM Villars ex Gochnat - 2n = 45.

Fields, meadows, roadsides. From Europe. [H. PRAEALTUM var. DECIPIENS W.D.J. Koch]

Hieracium robinsonii (Zahn) Fernald - 2n = 27.

Ledge crevices, rocky shores.

HIERACIUM SABAUDUM Linnaeus - 2n = 18, 27, (36).

Roadsides, waste places, fields. From Eurasia.

Hieracium scabrum Michaux - Sticky Hawkweed. 2n = 18.

Dry, open woods, fields, clearings, roadsides. [H. scabrum var. tonsum Fernald & H. St. John]

Hieracium umbellatum Linnaeus - Northern Hawkweed. 2n = 18, 27.

Dry, open woods, fields, woods margins, shores, thickets, clearings, roadsides. [H. canadense Michaux var. canadense; H. canadense var. fasciculatum (Pursh) Fernald; H. canadense var. hirtirameum Fernald; H. kalmii Linnaeus]

Hieracium venosum Linnaeus - Rattlesnake-weed. 2n = 18.

Dry, open, sandy woods, fields, clearings. [H. venosum var. nudicaule (Michaux) Farwell]

Hieracium hybrids

HIERACIUM X ATRAMENTARIUM (Nägeli & Peter) Zahn (pro species) - .

[H. AURANTIACUM Linnaeus X H. PILOSELLOIDES Villars]

Hieracium X fassettii Lepage - .

[H. X fernaldii Lepage; H. scabrum Michaux X H. umbellatum Linnaeus]

HIERACIUM X FLORIBUNDUM Wimmer & Grabowski (pro species) - .

[H. CAESPITOSUM Dumortier X H. LACTUCELLA Wallroth]

HIERACIUM X FUSCOATRUM Nägeli & Peter - .

[H. AURANTIACUM Linnaeus X H. CAESPITOSUM Dumortier]

HIPPURIS (Family: Plantaginaceae)

Hippuris vulgaris Linnaeus - Mare’s-tail. 2n = 32.

Shallow, quiet waters of rivers, freshwater pools, ponds and lakes.

HOLCUS (Family: Poaceae)

HOLCUS LANATUS Linnaeus - Velvet Grass. 2n = 14 + (0-2)B, (28).

Meadows, roadsides, sterile fields. From Europe.

HOLCUS MOLLIS Linnaeus - . 2n = 14, 21, 28, 35, 42, (49).

Waste land. From Europe.

HOLOSTEUM (Family: Caryophyllaceae)

HOLOSTEUM UMBELLATUM Linnaeus subsp. UMBELLATUM - Jagged Chickweed. 2n = 20, (40).

Fields, roadsides, waste places. From Mediterranean region, southwestern Asia.

HOMALOSORUS (Family: Woodsiaceae)

Homalosorus pycnocarpos (Sprengel) Pichi Sermolli - Narrow-leaved Spleenwort. 2n = 80.

Moist, mostly calcareous, wooded slopes, ravines, and bottoms. [Athyrium pycnocarpon (Sprengel) Tidestrom; Diplazium pycnocarpon (Sprengel) M. Broun] NEBC herbarium image

HONCKENYA (Family: Caryophyllaceae)

Honckenya peploides (Linnaeus) Ehrhart subsp. robusta (Fernald) Hultén - Seabeach Sandwort. 2n = ?

Sea beaches, dunes above high tide. [Arenaria peploides Linnaeus var. robusta Fernald]

HORDEUM (Family: Poaceae)

HORDEUM BRACHYANTHERUM Nevski subsp. BRACHYANTHERUM - . 2n = 21, 28, 42.

Wool waste. From farther west.

Hordeum jubatum Linnaeus subsp. jubatum - Squirrel-tail Grass. 2n = (14), 28, (56).

Roadsides, railroads, salt marshes, beaches.

HORDEUM MURINUM Linnaeus subsp. LEPORINUM (Link) Arcangeli - . 2n = (14), 28, 42.

Moist waste places. From Europe. [H. LEPORINUM Link]

HORDEUM PUSILLUM Nuttall - Little Barley. 2n = 14, (28).

Roadsides, marsh borders. From farther south.

HORDEUM VULGARE Linnaeus - Barley. 2n = 14, (28), (70).

Waste areas, roadsides. From Europe. [H. VULGARE var. TRIFURCATUM (Schlechtendal) Alefeld]

HOSTA (Family: Asparagaceae)

HOSTA LANCIFOLIA Trattinnick - . 2n = 60.

Thickets, roadsides, waste places. From eastern Asia. [H. JAPONICA (Thunberg) Voss]   VT herbarium image

HOSTA VENTRICOSA (Salisbury) Stearn - Blue Plantain-lily. 2n = 60, 120.

Rich woods along streams, moist banks. From eastern Asia.   NEBC herbarium image

HOTTONIA (Family: Primulaceae)

Hottonia inflata Elliott - American Featherfoil. 2n = 20, 22.

Muddy ponds, pools, swamps, backwaters of streams.

HOTTONIA PALUSTRIS Linnaeus - Water Violet. 2n = 20.

Muddy ponds, pools. From Eurasia

HOUSTONIA (Family: Rubiaceae)

Houstonia caerulea Linnaeus - Bluets. 2n = 16, 32, (36), 48.

Fields, usually moist, meadows, open woods, streambanks, swamps, roadsides. [H. caerulea var. faxonorum Pease & A.H. Moore; Hedyotis caerulea (Linnaeus) Hooker]

Houstonia longifolia Gaertner - . 2n = 12.

Dry, open woods, hillsides, rocky or gravelly soil. [Hedyotis longifolia (Gaertner) Hooker -- illegitimate name]

Houstonia purpurea Linnaeus var. calycosa A. Gray - . 2n = ?

Dry fields, open woods, slopes. [H. lanceolata (Poiret) Britton; Hedyotis lanceolata Poiret; H. purpurea (Linnaeus) Torrey & A. Gray var. calycosa (A. Gray) Fosberg]

HUDSONIA (Family: Cistaceae)

Hudsonia ericoides Linnaeus - Golden-heather. 2n = 20.

Sandy or rocky acidic, open soil, dunes, barrens, roadsides. [H. tomentosa Nuttall var. intermedia Peck]

Hudsonia tomentosa Nuttall - Beach-heath. 2n = 20.

Sandy, open soil, dunes, beaches, sandy shores.

Hudsonia hybrid

Hudsonia ericoides Linnaeus X H. tomentosa Nuttall - .

HUMULUS (Family: Cannabaceae)

HUMULUS JAPONICUS Siebold & Zuccarini - Japanese Hop. 2n = 16, 17, (18), (20).

Waste places, roadsides. From Asia.

HUMULUS LUPULUS Linnaeus var. LUPULUS - Common Hop. 2n = 20, (40).

Roadsides, waste places, fencerows. From Europe.

Humulus lupulus Linnaeus var. lupuloides E. Small - Common Hop. 2n = 20.

River thickets.

HUPERZIA (Family: Lycopodiaceae)

Huperzia appressa (Desvaux) Á. Löve & D. Lõve - . 2n = ca. 68.

Cliffs, talus slopes, damp, acidic rocks in alpine zones. [Lycopodium selago Linnaeus var. appressum Desvaux; The name Huperzia appressa Á. Löve & D. Lõve is here accepted only tentatively since a proper study of the Huperzia selago complex reviewing morphological and genetic evidence from specimens worldwide (including types) has not been done. The true status of Huperzia appressa (Desvaux) Á. Löve & D. Lõve, Huperzia appalachiana Beitel & Mickel, Huperzia selago var. densa Trevisan and Huperzia selago subsp.arctica (Tolmatchew) Á. Löve & D. Lõve can only be determined by such a study. Specimens mapped here are those filed as Huperzia appalachiana in the herbaria of the New England Botanical Club and Harvard University. Flora Europaea includes var. appressum under H. selago subsp. arctica, while the Flora of NW Europe does not recognize H. appressa. A Chinese molecular study (Ji et. al., 2008) uses the name Huperzia appressa. Flora of North America (1993) accepts Huperzia appalachiana without mention of appressa/appressum at any rank.] NEBC herbarium image

Huperzia lucidula (Michaux) Trevisan - Shining Clubmoss. 2n = 134.

Cool, moist woods in rich and acid soils. [Lycopodium lucidulum Michaux] CONN herbarium image

Huperzia selago (Linnaeus) Bernhardi ex Schrank & Martius - Mountain Clubmoss. 2n = 264, 268, 272.

Damp rocks, barrens, cold woods, in mountainous regions. [ Lycopodium selago Linnaeus] NEBC herbarium image

Huperzia hybrids

Huperzia appressa (Desvaux) Á. Löve & D. Lõve X H. lucidula (Michaux) Trevisan.

Huperzia X buttersii (Abbe) Kartesz & Gandhi.

[H. lucidula (Michaux) Trevisan X H. selago (Linnaeus) Bernhardi ex Schrank & Martius]

Huperzia X josephbeitelii A. Haines.

[H. appressa (Desvaux) Á. Löve & D. Lõve X H. selago (Linnaeus) Bernhardi ex Schrank & Martius]

HYBANTHUS (Family: Violaceae)

Hybanthus concolor (T.F. Forster) Sprengel - Green Violet. 2n = 48.

Shaded, calcareous talus.

HYDRANGEA (Family: Hydrangeaceae)

HYDRANGEA ARBORESCENS Linnaeus - Wild Hydrangea. 2n = 36, (38).

Roadsides, swamps, streambanks, thickets. From farther south and west.

HYDRANGEA PANICULATA Siebold - . 2n = (36), 72, (108).

Swamps, damp woodlands, roadsides, streambanks. From eastern Asia.

HYDRANGEA QUERCIFOLIA W. Bartram - . 2n = 36.

Dry, open hillsides. From southeastern United States.

HYDRANGEA RADIATA Walter - Silverleaf Hydrangea. 2n = 36.

Waste places. From southeastern United States. [H. ARBORESCENS Linnaeus subsp. RADIATA (Walter) E.M. McClintock]

HYDRASTIS (Family: Ranunculaceae)

Hydrastis canadensis Linnaeus - Goldenseal. 2n = 26.

Rich woods.

HYDRILLA (Family: Hydrocharitaceae)

HYDRILLA VERTICILLATA (Linnaeus (son)) Royle - . 2n = 16, 24, (32).

Ponds, lakes and streams. From the Old World.

HYDROCHARIS (Family: Hydrocharitaceae)

HYDROCHARIS MORSUS-RANAE Linnaeus - . 2n = (14), 28.

Near pond shore in .5m deep water. From Eurasia.

HYDROCOTYLE (Family: Araliaceae)

Hydrocotyle americana Linnaeus - Marsh Pennywort. 2n = 60.

Damp woodlands and thickets, swamps, meadows, wet fields, stream margins, freshwater shores, wet ditches.

Hydrocotyle umbellata Linnaeus - Water Pennywort. 2n = 48.

Pond shores.

Hydrocotyle verticillata Thunberg var. verticillata - Whorled Pennywort. 2n = 88+4

Pond shores.

Hydrocotyle verticillata Thunberg var. triradiata (A. Richard) Fernald - . 2n = ?

Damp soils. [H. prolifera Kellogg]

HYDROPHYLLUM (Family: Hydrophyllaceae)

Hydrophyllum canadense Linnaeus - . 2n = 18.

Damp, rich woodlands, mountain brooksides, rich humus at base of calcareous ledges.

Hydrophyllum virginianum Linnaeus var. virginianum - John’s-cabbage. 2n = 18.

Rich, deciduous, often wet, woodlands.

HYLODESMUM (Family: Fabaceae)

Hylodesmum glutinosum (Muhlenberg ex Willdenow) H. Ohashi & R.R. Mill - . 2n = 22.

Rich, dry or rocky woods. [Desmodium glutinosum (Muhlenberg ex Willdenow) Alph. Wood; D. acuminatum (Michaux) de Candolle]

Hylodesmum nudiflorum (Muhlenberg ex Willdenow) H. Ohashi & R.R. Mill - . 2n = ?

Rich, dry or rocky woods. [Desmodium nudiflorum (Linnaeus) de Candolle]

HYLOMECON (Family: Papaveraceae)

HYLOMECON JAPONICA (Thunberg) Prantl var. JAPONICA - . 2n = (12), 24.

Roadsides, woodland margins. From eastern Asia, Russia.

HYLOTELEPHIUM (Family: Crassulaceae)

HYLOTELEPHIUM ERYTHROSTICTUM (Miquel) H. Ohba - Garden Stonecrop. 2n = 48, 50.

Waste places, disturbed ground, roadsides, pond shores. From eastern Asia, Russia. [SEDUM ALBOROSEUM Baker; S. ERYTHROSTICTUM Miquel; S. SPECTABILE - misapplied]

HYLOTELEPHIUM SPECTABILE (Boreau) H. Ohba - Butterfly Stonecrop. 2n = 50, 51.

Dry, roadsides. From eastern Asia. [SEDUM SPECTABILE Boreau]

HYLOTELEPHIUM TELEPHIUM (Linnaeus) H. Ohba - Witches' Moneybags. 2n = 24, 48, (36).

Roadsides, waste places, old fields. From northern Eurasia. [SEDUM TELEPHIUM Linnaeus; S. PURPUREUM (Linnaeus) Schultes]

HYMENOXYS (Family: Asteraceae)

HYMENOXYS ODORATA de Candolle - Bitter Rubberweed. 2n = 22, (24), (28), 30.

Waste places. From farther west.

HYOSCYAMUS (Family: Solanaceae)

HYOSCYAMUS NIGER Linnaeus - Black Henbane. 2n = 34.

Roadsides, waste places, wool waste. From Eurasia, northern Africa.

HYPERICUM (Family: Hypericaceae)

Hypericum adpressum W.P.C. Barton - . 2n = 18.

Sandy or sphagnous pond shores and depressions.

Hypericum ascyron Linnaeus subsp. pyramidatum (Aiton) N. Robson - Great St. John’s-wort. 2n = ?

River thickets and meadows. [H. pyramidatum Aiton]

Hypericum boreale (Britton) E.P. Bicknell - . 2n = 16.

Swamps, bogs, meadows, shores, and other open, wet places. [H. mutilum Linnaeus subsp. boreale (Britton) J.M. Gillett]

Hypericum canadense Linnaeus - . 2n = 16.

Bogs, shores, swamps, marshes, vernal pools, open places in moist sand.

HYPERICUM DENSIFLORUM Pursh - . 2n = 16, 18.

Fields, roadsides. From farther south.

Hypericum ellipticum Hooker - . 2n = 16, 18.

Sandy or gravelly shores, meadows, marshes, swamps and other wet places.

HYPERICUM FRONDOSUM Michaux - . 2n = 18.

Fields, roadsides. From farther south.

Hypericum gentianoides (Linnaeus) Britton, Sterns & Poggenburg - Pineweed. 2n = 24.

Sandy, open soil, railroads, roadsides, fields, waste places.

Hypericum hypericoides (Linnaeus) Crantz subsp. multicaule (Michaux ex Willdenow) N. Robson - Great St. Andrew’s Cross. 2n = 18.

Dry sand plains. [H. stragulum W.P. Adams & N. Robson; Ascyrum hypericoides Linnaeus var. multicaule (Michaux ex Willdenow) Fernald]

Hypericum majus (A. Gray) Britton - . 2n = 16.

Damp fields, shores, wet roadsides, other open, wet places.

Hypericum mutilum Linnaeus subsp. mutilum - . 2n = 16.

Swamps, bogs, meadows, shores, and other open, wet places. [H. mutilum var. parviflorum Fernald]

HYPERICUM PERFORATUM Linnaeus subsp. PERFORATUM - Common St. John’s-wort. 2n = (16), 32, (48).

Dry, sandy, fields, roadsides, riverbanks, meadows, railroads, waste places. From Eurasia, northern Africa.

HYPERICUM PROLIFICUM Linnaeus - Shrubby St. John’s-wort. 2n = 18.

Sandy fields, roadsides. From farther south and west. [H. SPATHULATUM (Spach) Steudel]

Hypericum punctatum Lamarck - Spotted St. John’s-wort. 2n = (14), 16.

River thickets, meadows, swamps, woodlands, fields, openings, railroads, roadsides.

Hypericum hybrids

Hypericum canadense Linnaeus X H. majus (A. Gray) Britton - .

Hypericum canadense Linnaeus X H. mutilum Linnaeus subsp. mutilum - .

Hypericum X dissimulatum E.P. Bicknell (pro species) - .

[H. canadense Linnaeus X H. boreale (Britton) E.P. Bicknell]

Hypericum majus (A. Gray) Britton X H. mutilum Linnaeus subsp. mutilum - .

HYPOCHAERIS (Family: Asteraceae)

HYPOCHAERIS GLABRA Linnaeus - 2n = (8), 10, (12).

Wool waste, fields. From Eurasia, northern Africa.

HYPOCHAERIS RADICATA Linnaeus - Common Cat’s-ear. 2n = 8.

Roadsides, fields, waste places. From Eurasia, northern Africa.

HYPOXIS (Family: Hypoxidaceae)

Hypoxis hirsuta (Linnaeus) Coville - Common Stargrass. 2n = 28.

Open woods, fields.

HYSSOPUS (Family: Lamiaceae)

HYSSOPUS OFFICINALIS Linnaeus - Hyssop. 2n = 12, (13).

Roadsides, dry fields, waste places. From Eurasia, northwestern Africa.

Designed by Ray Angelo. Revised March 16, 2023