Key to Hydrocharitaceae

View taxon page for Hydrocharitaceae

Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

1. Plants floating (rooted in mud when stranded); leaves (when floating) with swollen spongy cells abaxially ..... LIMNOBIUM

1' Plants submersed to emergent; leaves without swollen spongy cells abaxially

2. Leaves 

basal 

At or near the base of a plant or plant part. Especially said of leaves clustered near the ground or of a placenta confined to the base of an ovary.

, petioled, 

alternate 

1. Arranged singly, often spirally, along an axis - e.g., one leaf per node. 2. Occurring in different ranks, appearing to be between, not directly above or below, as 'stamens alternate petals'.

, lower, submersed blades 

elliptic 

In the shape of a flattened circle or ellipse; wider than linear

to 

ovate 

Egg-shaped (i.e., widest below the middle) in two dimensions (i.e., in one plane), as a leaf.

, upper, floating or emergent blades ovate to 

cordate 

Heart-shaped; often pertaining to a leaf in which the blade base on both sides of the petiole is rounded and convex.

or 

reniform 

Kidney-shaped; often pertaining to a leaf in which the blade base on both sides of the petiole is rounded and concave.

– flower 

bisexual 

Both male and female reproductive parts occurring and functional in the same plant or structure (e.g., flower, spikelet, inflorescence).

, emergent ..... [OTTELIA]

2' Leaves cauline, 

sessile 

Without a petiole, peduncle, pedicel, or other kind of stalk.

, 

opposite 

1. Arranged in pairs along an axis - e.g., two leaves per node. 2. Occurring in the same rank, directly above or below, as 'stamens opposite petals'. 3. Located directly across from.

to 

whorled 

Arranged in groups of three or more at nodes or positions along an axis (e.g., three leaves per node).

, 

blade 

Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped.

 

oblong 

Longer than wide, with nearly parallel sides; wider than linear.

or 

linear 

Elongate, with nearly parallel sides; narrower than elliptic or oblong.

3. Perianth 0; leaves ± opposite to ± whorled; seeds smooth or pitted ..... NAJAS

3' Perianth present; leaves opposite or generally whorled; seeds smooth

4. Leaves 1.2–4 cm, 2–5 mm wide; staminate flowers 2–3, petals 8–10 mm ..... EGERIA

4' Leaves < 1.5(2) cm, < 3 mm wide; staminate flowers 1, petals generally <= 5 mm

5. Leaves often 2 per 

node 

Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise.

 proximally, 3–7 distally, minutely 

serrate 

Having margins with sharp, fine to coarse teeth generally pointing tipward, not outward; margins with such teeth on such primary teeth are doubly serrate.

, midrib abaxially ± smooth ..... ELODEA

5' Leaves generally 4–8 per node, coarsely serrate, midrib abaxially prickled or not ..... HYDRILLA

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Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on .

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