An Illustrated Flora of the Northern United States, Canada and the British Possessions/Zannichelliaceae

Family 3.   Zannichelliàceae   Dumort.   Anal. Fam. 61.   1829.*
Pondweed Family.

Perennial marine or fresh-water plants with floating or submerged leaves, or both. Leaf-blades petioled or sessile, capillary or expanded into a proper blade, or rarely reduced to terete phyllodes. Flowers perfect or monoecious, in sessile or peduncled spikes, or in clusters in the axils of the leaves. Perianth none, but flowers sometimes enclosed in a hyaline sheath. Androecium of 1-4 stamens. Anthers extrorse, 1-2-celled, the connective sometimes becoming perianth-like. Gynoecium of 1-4 distinct, 1-seeded carpels. Fruits mostly nut-like or drupelike, sessile or stipitate. Endosperm wanting.


* Text of this family and of the two following ones contributed to the first edition by the late Rev. Thomas Morong, revised for this edition by Mr. Norman Taylor.


About 4 genera and 70 species of wide geographic distribution, most abundant in temperate regions. The months noted in the descriptions indicate the fruting period.

Flowers perfect; stamens more than 1.
Stamens 4; fruit sessile. 1. Potamogeton.
Stamens 2; fruit stalked. 2. Ruppia.
Flowers monoecious; stamen 1. 3. Zannichellia.


1.   Potamogèton   L.   Sp. Pl. 126.   1753.

Leaves alternate or the uppermost opposite, often of 2 kinds, submerged and floating, the submerged mostly linear, the floating coriaceous, lanceolate, ovate or oval. Spathes stipular, often ligulate, free or connate with the base of the leaf or petiole, enclosing the young buds and usually soon perishing after expanding. Peduncles axillary, usually emersed. Flowers small, spicate, green or red. Perianth none. Stamens 4. Anthers sessile, the connective dilated, perianth-like (Fig. 186). Ovaries 4, sessile, distinct, 1-celled, 1-ovuled, attenuated into a short erect or recurved style, or with a sessile stigma. Fruit of 4 ovoid or subglobose drupelets, the pericarp usually thin and hard or spongy. Seeds crustaceous, campylotropous, with an uncinate embryo thickened at the radicular end. [Greek, in allusion to the aquatic habitat.] Water Spike.

About 65 well-defined species, natives of temperate regions. Besides the following, about 3 others occur in the southern parts of North America. Type species Potamogeton natans L.

Stipules axillary and free from the rest of the leaf.
With floating and submerged leaves.
Nutlets more or less pitted. 1. P. natans.
Nutlets not pitted. 2. P. Oakesianus.
Submerged leaves with a proper blade.
Submerged leaves of 2 kinds, lanceolate and oval or oblong
Uppermost broadly oval or elliptical, lowest lanceolate. 3. P. amplifolius.
Uppermost lanceolate and pellucid, lowest oblong and opaque. 4. P. pulcher.
Submerged leaves all alike, capillary or linear-setaceous.
1-nerved or nerveless. 25. P. Vaseyi.
3-nerved. 26. P. lateralis.
Submerged leaves all alike, linear.
Nearly the same breadth throughout, obtusely pointed, coarsely cellular-reticulated in the middle. 5. P. epihydrus.
Broader at base, acute, without cellular-reticulation. 9. P. heterophyllus.
Submerged leaves all alike, lanceolate.
Uppermost leaves petioled, lowest sessile. 6. P. alpinus.
All the leaves petioled.
Floating leaves large, broadly elliptic, rounded or subcordate at base. 11. P. illinoensis.
Floating leaves narrowly elliptical, tapering at base. 7. P. americanus.
Floating leaves mostly obovate or oblanceolate, tapering at base. 8. P. Faxoni.


  1.  Potamogeton nàtans  L.
Common Floating Pondweed.   Fig. 174.

Potamogeton natans L. Sp. Pl. 126. 1753.

Stems 2°-4° long, simple or sparingly branched.   Floating leaves thick, the blade ovate, oval or elliptic, 2'-4' long, 1'-2' wide, usually tipped with a short abrupt point, rounded or subcordate at the base, many-nerved; submerged leaves reduced to phyllodes or bladeless petioles which commonly perish early and are seldom seen at the fruiting period; stipules sometimes 4' long, acute, 2-keeled; peduncles as thick as the stem, 2'-4' long; spikes cylindric, very dense, about 2' long; fruit turgid, 2"-2¼" long, about 1¼" thick, scarcely keeled, narrowly obovoid, slightly curved on the face; style broad and facial; nutlet hard, more or less pitted or impressed on the sides, 2-grooved on the back; embryo forming an incomplete circle, the apex pointing toward the base.

In ponds and streams, Nova Scotia to British Columbia, New Jersey, Missouri and Nebraska. Also in Europe and Asia.  July-Aug.  Called also Tench-weed, Batterdock, Deil's-spoons.


2.  Potamogeton OakesiànusRobbins.
Oakes' Pondweed.   Fig. 175.

Potamogeton Oakesianus Robbins in A. Gray, Man. Ed. 5, 485.  1867.

Stems very slender, often much branched from below.   Floating leaves elliptic, mostly obtuse, rounded or slightly subcordate at the base, 1'-2' long, 5"-9" wide, 12-20-nerved; petioles 2'-6' long; submerged leaves mere capillary phyllodes, often persistent through the flowering season; peduncles 1'-3' long, commonly much thicker than the stem, mostly solitary; spikes cylindric, ½'-1' long; stipules acute, hardly keeled; fruit obovoid, about 1½" long, l" thick, nearly straight on the face, 3-keeled, the middle keel sharp; style apical or subapical; sides of the nutlet not pitted, but sometimes slightly impressed; embryo circle incomplete, the apex pointing toward the base.

In still water, Anticosti to Wisconsin and New Jersey.  Summer.


  3.  Potamogeton amplifòliusTuckerm.
Large-leaved Pondweed.   Fig. 176.

Potamogeton amplifolius Tuckerm. Am. Journ. Sci. (II.) 6: 225.  1848.

Potamogeton amplifolius ovalifolius Morong; A. Benn. Journ. Bot. 42: 70.  1904.

Stems long, simple or occasionally branched. Floating leaves oval or ovate, abruptly pointed at the apex, rounded at the base, 2'-4' long, 1¼'-2' wide, many-nerved; petioles 3'-5' long; submerged leaves mostly petioled, the uppermost often elliptic or oval, 3'-6' long, 1'-2½' wide, the lowest lanceolate, often 8' long, with the sides closed and assuming a falcate shape; stipules tapering to a long sharp point, sometimes 4' long; peduncles thickened upward, 2'-8' long; spikes cylindric, 1'-2' long; fruit 2"-2½" long, 1¼" thick, turgid, the pericarp hard, obliquely obovoid, 3-keeled; face more or less angled; style subapical; embryo slightly incurved.

In lakes, Ontario to British Columbia, south to Georgia and Nebraska.  July-Sept.


4.  Potamogeton púlcher  Tuckerm.
  Fig. 177.


  5.  Potamogeton epihỳdrus  Raf.
  Fig. .


6.  Potamogeton alpìnus  Balbis.
  Fig. .


  7.  Potamogeton americànus  Cham. & Schl.
  Fig. 180.


8.  Potamogeton Fáxoni  Morong.
  Fig. 181.


  9.  Potamogeton heterophýllus  Schreb.
  Fig. 182.


10.  Potamogeton vàrians  Morong.
  Fig. 183.


  11.  Potamogeton illinoensis
  Fig. 184.


12.  Potamogeton angustifolius
  Fig. 184.


  13.  Potamogeton lucens
  Fig. 186.


14.  Potamogeton praelongus
  Fig. 187.


  15.  Potamogeton perfoliatus
  Fig. 188.


16.  Potamogeton mysticus
  Fig. 189.


  17.  Potamogeton confervoides
  Fig. 190.


18.  Potamogeton crispus
  Fig. 191.


  19.  Potamogeton compressus
  Fig. 192.