• Category
  • Length Range
    27.5-56.6 µm
  • Width Range
    8.6-11.8 µm
  • Striae in 10 µm



Valves are elliptic-lanceolate with convex margins. The apices are acutely rounded. The axial area is narrow. A large rounded central area is formed by one or two shorter striae on each side. Thre raphe is filiform and straight. Proximal raphe ends are slightly deflected to one side and tipped with expanded pores. Distal raphe ends are sickle-shaped. Striae are broad and widely separated, weakly radiate near the valve center and becoming convergent towards the apices.


The specimens of P. borealis var. lanceolata pictured and described on this web page were collected in May 2007 from a shallow rainwater puddle on Stinkingwater Pass in Harney County, eastern Oregon (photo below).

Stinking Water Pass
Credit: Loren Bahls
Stinkingwater Pass, Harney County, eastern Oregon.

Original Description

  • Author
    Hust. 1934

Original Images

Pinnularia Borealis Lanceolata Origimag2002
Pinnularia Borealis Lanceolata Origimag1001

Cite This Page

Bahls, L. (2014). Pinnularia borealis var. lanceolata. In Diatoms of North America. Retrieved July 15, 2024, from https://diatoms.org/species/pinnularia_borealis_var._lanceolata


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Pinnularia borealis var. lanceolata from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.