Key to Apocynaceae

View taxon page for Apocynaceae

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

1. Filaments fused into filament 

column 

Structure at the center of an orchid flower formed by fusion of stamen(s) and style.

, generally with 5 free or fused, ± elaborate appendages abaxially; anthers fused into anther 

head 

1. A dense, often spheric inflorescence of sessile or subsessile flowers.
2. In Asteraceae and some other groups, a head-like inflorescence is one in which sessile or subsessile inflorescence units (e.g., heads in Asteraceae, umbels enclosed by involucres in Eriogonum), instead of individual flowers, are attached in a short dense cluster without an evident axis or branches.

around and fused to pistil head; pollen removed in pairs of pollinia; nectaries in stigmatic chambers (genera formerly treated as Asclepiadaceae)

2. Filament column ± without appendages ..... Funastrum utahense

2' Filament column with appendages

3. Filament column appendages fused into 5-lobed, cup- or plate-like structure around anther head ..... MATELEA

3' Filament column appendages free

4. Filament column appendages hollow (possibly due to complete fusion of margins); ring of tissue at base of corolla present ..... FUNASTRUM

4' Filament column appendages solid (margins converging, nearly meeting or not, not fused); ring of tissue at base of corolla 0

5. Filament column appendage margins converging but not nearly meeting abaxially; flowers in raceme- or panicle-like 

cymes 

1. In flowering plants excluding Asteraceae and some other groups, a branched inflorescence in which the central or uppermost flower opens before the peripheral or lowermost flowers on any axis. see 2. In Asteraceae and some other groups, a cyme-like inflorescence is one in which the central or uppermost inflorescence units (e.g., heads in Asteraceae, umbels enclosed by involucres in Eriogonum), instead of individual flowers, develop and mature before the peripheral or lowermost inflorescence units on any axis.

; stem twining ..... ARAUJIA

5' Filament column appendage margins converging and meeting or nearly meeting adaxially (to form hood); flowers in umbel-like cymes; stem 

prostrate 

Lying flat on the ground.

to 

erect 

Upright; vertically oriented.

..... ASCLEPIAS

1' Filaments free, unappendaged; anthers free, lying against, adherent to pistil head or not; pollen ± free, not removed in pollinia; nectaries 0 or near ovaries (genera formerly treated as Apocynaceae)

6. Seed glabrous; stamens attached near top of corolla tube, near level of stigma

7. Leaves 

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'.

to subwhorled; plant erect ..... AMSONIA

7' Leaves 

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 subopposite; plant erect or sprawling

8. Corolla pink, tube ± 

cylindric 

Elongate, with parallel sides and, at any point, round in transverse section.

; plant erect ..... [Catharanthus roseus]

8' Corolla purple-blue (white), tube 

funnel-shaped 

Widening from the base more or less gradually through the throat into an ascending, spreading, or recurved limb; often applied to a fused calyx or corolla.

; plant sprawling ..... VINCA

6' Seed with tuft of long hairs at 1 end; stamens attached at or near base of corolla tube, below level of stigma, or appearing so

9. Plant shrub, small tree; leaves generally 

whorled 

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

or subwhorled (opposite); nectaries 0; sap not milky ..... NERIUM

9' Plant 

perennial 

Completing life cycle (germination through death) in more than two years or growing seasons, generally non-woody (at least above ground) to woody; includes perennial herbs as well as subshrubs to trees; the abbreviation 'per' only refers to perennial herb, not to the word 'perennial' alone.

 herb; leaves opposite; nectaries 5, free or fused; sap milky

10. Leaves, stems, roots not fleshy; flower < 8 mm, in generally >> 6-flowered 

cyme 

1. In flowering plants excluding Asteraceae and some other groups, a branched inflorescence in which the central or uppermost flower opens before the peripheral or lowermost flowers on any axis. see 2. In Asteraceae and some other groups, a cyme-like inflorescence is one in which the central or uppermost inflorescence units (e.g., heads in Asteraceae, umbels enclosed by involucres in Eriogonum), instead of individual flowers, develop and mature before the peripheral or lowermost inflorescence units on any axis.

; nectaries 5, free ..... APOCYNUM

10' Leaves, stems, roots fleshy; flower > 15 mm, in 2–6-flowered cyme; nectaries 5, fused into a 5-lobed disk ..... CYCLADENIA

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