• Category
  • Length Range
    27.0-150.0 µm
  • Width Range
    4.0-5.0 µm
  • Striae in 10 µm



The valves are linear to linear-lanceolate, with apices acutely rounded. The raphe keel is not positioned on the margin, but slightly off the margin. Fibulae are distinct, irregular in size, and relatively broad and with a density of 7-9 in 10 µm. A prominent central nodule is present. Striae are indistinctly punctate and fine, but visible under LM.

Original Description

  • Basionym
    Homoecladia filiformis
  • Author
    W.Sm. 1856

Original Images


Cite This Page

Kociolek, P. (2011). Nitzschia filiformis. In Diatoms of North America. Retrieved May 18, 2024, from https://diatoms.org/species/nitzschia_filiformis


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Nitzschia filiformis 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.