An old canal of the Potomac below Great Falls, looking downstream, the main Potomac in the distance. Ricker, the first list of plants from our region was included in the Florula Columbiensis.2 The second list was compiled by John A. The geology of the region in relation to its flora has been briefly discussed by Edgar T.
Coals also occur to some extent as caps on the hills along the edge of the Piedmont. There are many aquatic and semi-aquatic plants in the water of the canal and along the edge. The canal towpath offers pedestrians the most convenient way to observe.
One of the most conspicuous of these is Phlox subutata, common on the rocks along the towpath. There are marshes bordering the right bank of the Potomac between Washington and Vemonberg.
LEAVES OPPOSITE
Most leaves on any plant have more than 5 leaflets, but some leaves occasionally have only 5 leaflets. Planting trees; flowers, pistillate and stamens, usually appear before the leaves, in small clusters or in panicles; fruit a winged samara. Plant shrubs; flowers perfect, appearing after the leaves, in broad, flattened cymes; fruit juicy, berry-like Sambucus (p. 261).
Leaflets not glandular, 3 to many, conspicuously toothed; fruit a dry or slightly juicy drupe; erect or climbing shrubs. Leaves, at least the upper ones, in whorls of 3, glabrous, pinnate; flowers in dense spherical heads. Leaves rounded at tip; flowers axillary, corolla tubular or funnel-shaped; fruit a many-seeded black or red berry Lonicera (p. 259).
Leaves of widest leaves near or above middle, obtuse or usually acute or narrowed at base. Flowers in flat cymes or rarely in a dense head, surrounded by 4 petal-like white leaflets; 4 or 5 stamens.
PLANTS ARMED WITH SPINES
LEAVES ENTIRE
Leaves peltate, the petiole fixed at the bottom Bide near the base; fruit juicy, l-seeded. Blades of the leaves acute or tapering at the base, not lobed; tendrils none; fruit a dehiscent capsule Cdastrus (p. 199). Leaf blades heart-shaped or truncate at the base, usually lobed; plants with tendrils; fruit a juicy berry VITACEAE (p. 201).
Leaves with 2 sharp lobes at the apex and with a lobe on each side near the base, not toothed, glabrous.
BLADES OF THE LEAVES, AT LEAST SOME OF THEM, LOBE
Teeth of leaves blunt; fruit a woody capsule; flowers appear in autumn, bright yellow; shrub Hamamelis (p. 172). Teeth of the leaves acute; fruit no woody capsule; flowers appear in spring or summer; trees or rarely shrubs. Fruit a dry capsule; teeth of the leaves without bristly tips; flowers in a terminal, long-stalked cluster; petals distinguish Chimaphila (p. 221).
Trees or shrubs; leaf teeth often with punctured tips .FAGACEAE (p. 137), Fruit not a nut enclosed in a prickly brush or warts. Leaves with net veins; flower parts usually in 4 or 5, but rarely in 3; plants never with bulbs. The leaf blades are deeply joined at the base, or lanceolate (the petiole attached to the middle of the blade).
Flowers minute, solitary or 2 or 3 together in leaf axils, sessile; Nut-shaped fruit, with 4 lobes. Pistillate and staminate flowers in separate heads, involucres of fertile heads hard and woody, Prickly Ambrosia (p. 268).
LEAVES WITH STIPULES
The leaf plates are only toothed, glabrous; flowers perfect, in small heads, each head surrounded by 4 bracts Mikanla (p. 275). Flowers are not sessile in dense heads or spikes, sometimes in dense inflorescences, then stalked. The leaf plates are very fluffy, visibly toothed; flowers in cymes, white, petals different; capsule split almost to the base of Saxifraga (p. 172).
Leaf blades glabrous, entire or very shallowly toothed; flowers not in cymes; capsule not cleft. Leaf blades are not kidney-shaped, longer than wide, usually narrow, but sometimes oval or triangular. Flowers not crowded with a spike surrounded by a shoulder; fruit a capsule, or fleshy and many-seeded.
Flowers not in racemes, usually blue or orange and large; plants without glandular pubescence IEIDACEAI (p. 126). The flowers are not borne in dense heads in a common receptacle surrounded by an involucre of bracts a, aa.
COROLLA QAMOPETALOUS (OF UNITED PETALS), ALWAYS PRESENT, CONSPICUOUS, COLORED
Fruit a berry; never plants with bulbs; sometimes leaves a single whorl at the top of the tribe CONVALLARIACEAE (p. 123). Plants with leaf stalks; leave them all or part of them opposite, the blades simple, entire, net-veined. Corolla much longer than the calyx; fruit loose, not colored, usually with more than 3 seeds; leaves do not lock together.
Capsule not contracted at base; seeds not on hooks; stamens as long as corolla lobes. Stamens alternate with corolla lobes; flowers never bright yellow nor solitary in axils. Stems usually more than 1 flowered, flowers not single on long thin peduncles, not nodding; smaller sepals, not thick and leathery.
Flowers in simple racemes or bunches, very irregular, the sepals 5, of which 3 are small, 2 are large and colored like the 3 petals. Leaves not whorl-like, or, if so, the leaves not fleshy; branches of the inflorescence not very one-sided.
SEPALS UNITED, AT LEAST BELOW, OFTEN NEARLY TO THE APEX
Plants glabrous; leaves only 2, held at the top of the stem; flower 1, placed between the leaves, wkh large white petals; with fruit juice. Flowers erect and pistillate, both types separate from the heads; pistillate heads prickly, prickly; flower ray none; green or yellow flowers. The leaf blades are very fleshy and succulent, obovate or terete; fruit a many-seeded capsule opening by a lid.
Upper leaf blades toothed, lower deeply lobed; plants ul very humid situations, axillary sessile flowers without petals. Ash borne at the base of the ovary or fruit and free from it; corolla usually yellow or white, never red. Streams in cross-section showing vascular strands or threads irregularly distributed through the gills, as in cornstalks; embryo with a single cotyledon; flower parts usually in 3 or 6, never in 5; leaves usually with parallel veins.
Stems in cross section showing a central pith surrounded by a circle or ring of vascular strands, these often fused into a zone of wood; embryo with two cotyledons; parts of the flower usually in 4's or 5*s; leaves net-veined. This claw has also been called exogenous because, especially in woody plants, there is a division of the trunk into wood and bark with a growing (cambium) layer in between, as the increase in diameter occurs by additions from the cambium to the outermost part of the tree and to the inner part of the bark.
THE DISTRICT OP COLUMBIA. 45
PISTILS HOBS THAN ONE, DISTINCT OR NEARLY SO
Flowers in cymes; stone 2-celled COBNACEAE Flo n i pan cles; stone 1-celled OLEACEAE Fruit dry (aril fleshy in Euonymm),. Stamens not equal in number to the petals, or, if equal in number, alternate with them. Stems not succulent and flat, leaves developed; ovary superior (calyx slightly adhesive in Castalia).
OVARY 1-CELLED
- PTE RET IS
- PTERIDITJM
- CAMP TOSOBXTS
- ANCHISTEA
- ATHTOIUM
- POLYFODIUM
- ONOCLEA L
- POLYPODIUM L
- POTAMOGETON
- NAIADACEAE
- ALISMA L
- ANACHARIS
- VALLISNERIA,
- VALLISNERIA I,
- PHALARIDEAE
- ERIANTHUS
forests; abundantly; attains its best development in the rich hill forests on the Virginia side of the upper Potomac. Sporangia are located on the back of the segments in certain sori, clearly separated from the margin. The leaves of the terminal branches are small, mostly imbricate, adnate and adnate, arranged in 4 rows.
A few trees in Hock Creek Park and on the bluffs of the Virginia coast of the Potomac above Cabin John. Basal auricles of the leaves rounded, toothed on the even maigin; leaves linear, the teeth frequent. Basal auricles of the leaves pectinate, serrated on the irregular parts; leaves filiform, the teeth sparse 2.
Fertile pedicels shorter than the triangular-lanceolate apices; beak of achene almost erect. Spikelets borne only on one side of the axis (1-sided arrangement somewhat obscure in Gymnopogon and Leptochloa) vxu.
SOBGHASTBTJM
- CENCHBUS
- PANICUM
- SPOROBOLTJS
- ARRHENATHEBUM
- TBISETUM
- LEPTOCHLOA
- PHBAGMITES
- TBEDENS
- EBAGBOSTIS
- DACTYLIS, Spikelets neither strongly flattened nor in clusters
- FESTTJCA
- ELYMTJS
- AGBOPYBON
- SEC ALE
- TRIPSACTJM L
- ANDBOFOGON L
- PASPALUM L
- PANICTJM L
- ZIZANIA L
- PHALABIS L
- ANTHOXANTHVM L
- PHLETJM L
- ALOPECTJBTTS L
- CINNA L
- AVENA L
- MELICA L
- SECALE L
- TBITICTJU L
- DTJLICH1UM
- KYLLINGA
- ELEOCHABIS
- STENOFHYLLUS
- SCIBPTJS
- ERIOPHORUM
- CYPEBUS L
- ACORUS L
- ORONTIUM L
- SPIRODELA
- TRADES CANTIA
- PONTEDEBIA
- PONTEDEBIA L
- JUNCUS
- UVTJLABIA
- TOFTELDIA
- CHAMASUBIUM
- CHBOSPEBMA
- VERATRTJM L
- ORNITHOGALUM
- HEMEROCA1LIS
- ALETRIS
- ALIIUM L
- HEMEBO CALLIS L
- POLYGONATUM
- ASPARAGUS L
- MEDEOLA L
- IRIS L
- TIPTTLABIA
- CYFMPEDIUM
- PERAMIUM
- LIPARIS
- CYPRIPEDIUM
- TRIPHORA
- ORCHIS L
- LLMODORUM L
- ARETHUSA L
- SERAPIAS L
- SAURTJSUS L
- MYRICA L
- BETULA
- CARPINTJS
- CARFINUS L
- CORYLTTS L
- QUEECUS
- FAGTT8 L
- TJLMTJS
- CELTIS
- CANNABIS
- CANNABIS L
- PARIETABIA L
- ABISTOLOCHIA L
- ASARTJM L
- PER SIC ARIA
- PLEUBOPTERT7S
- CHENOPODIUM L,
- SALSOLA L
- AMABANTHUS
- ALLION1A L
- MOLLUGO L
- PORTULACA, Leaves 2 on each stem; perennials with tuberous roots,the leaves nearly linear,
- POBTULACA L,
- CLAYTONIA L
- ANYCHIA
- SCLEBANTHTTS L
- SAGINA
- SPERGTTLA L
- ALSINE L
- ARENARIA L
- AGROSTEMMA L
- SILENT L
- LYCHNIS L
- DIANTHUS L
- SAPONARIA L
- NYMPHAEA
- NYMPHAEA L
- BRASENIA
- CLEMATIS
- CIMICIFUGA
- AQUILEGIA
- TRAUTVETTERIA
- THALICTRUM
- CIMICIFUGA L
- ACONITTJM L
- CLEMATIS L
- FODOPHYLIUM L
- MAGNOLIA, Leaver lobod, truncate or broadly notched at the apex; flowers greenish yellow,
- XJBIODENDBON
- MAGNOLIA L
- LIRIODENDHON L
- SANG-UINABIA L
- CHELIDONIUM L
- CAFNOEDES
- FTJMARIA L
- BBASSICA
- CABDAMENE
- ARABIS
- SIN APIS
- BRASSICA
- ERYSIMUM
- DRABA L
- SISYMBBIUM L
- LEPIDIUM L
- SINAPIS L
- BRASSICA L
- BAPHANUS L
- CLEOME L
- SARRACENIA L
- PODOSTEMACEAE
- PENTHOBTJM L
- CHBYSO SPLENIUM
- HETTCHERA L
- MITELLA L
- TIABELLA L
- HYDRANGEA L
- ITEA L
- RIBES L
- LIQUIDAMBAR
- HAMAMELIS L
- LIQTCDAMBAB L
- BITBTJS
- FBAGABIA L
- APHANES L
- SANGUISOBBA L
- POTERIUM L
- AMELANCHIEB
- PYBTJS L
- AMYGDALUS L
- PEUNTJS L
- GLEDITSIA
- CHAMAECRISTA
- CERCIS L
- GLEDITSIA L
- VICIA ft
- CYTISUS
- BAPTISIA, Stems climbing, twining
- PHASEOLT7S
- CBOTALABIA L
- LUPINUS L
- GENISTA L
- MEDICAGO L
- CBACCA L
- BOBINIA L
- ASTRAGALUS L
- CLITOBIA L
- GLYCZNE L
- PHASEOLUS L
- PUERARIA DO
- GERANIUM
- ERODIUM L
- PTELEA L
- PHYLLANTHTTS L
- LIMITANTHACEAE
- TOXICODENDRON
- BHUS
- SCHMALTZIA
- EUONYMUS L
- CELASTBITS L
- STAPHYLEA L
- CEANOTHUS L
- TXLXA L
Flowers solitary along the branches of the inflorescence, prophyllate (that is, each subtended by two bracteoles in addition to the bracts at the base of the stalk).
