logo Calflora Plant Distribution Help
The Plant Distribution application shows the range of a particular plant in California by highlighting the watersheds in which the plant has been observed as yellow or orange. It can also show observation points on top of the watershed polygons.

To use the application, begin by dragging the map to an area of interest, and then zoom in to look at the data in more detail.

After dragging, click on the map. The point where you click is indicated by a red cross , and the coordinates of the point are shown above the map on the left.

DISPLAY
The application begins by showing the Terrain map type. When you want to zoom in closer than the Terrain map type will allow, switch to the Satellite map type (upper right).

Watershed Polygons
When the application first comes up, it highlights the watersheds indicating the possible range of the plant -- in other words, the widest range that can be imputed from available observation data.

The presence of the plant in a watershed is considered confirmed (yellow) if there are two or more observations in the watershed. The presence of the plant in a watershed is considered possible (orange) if there is a single observation in the watershed.

Check confirmed range to show only watersheds indicating the confirmed range of the plant.

Observations
Check Individual observations to display observations on top of the watershed polygons.

When you click on an observation point , an info window appears showing a summary of the observation, with a link to see the full details. If the record is from the Consortium of California Herbaria (CCH), this link will take you to the CCH page for the observation. Otherwise this link will take you to the Calflora page for the observation.

TOOLS
Open the TOOLS menu to get access to these functions.

SHARE THIS PAGE
When you click on this link, the current state of the page is added to your browser's URL. After pressing this link, you can

  • use the browser to bookmark the URL;
  • copy the URL and email it to someone; or
  • use the browser's back button later to return to this state.

Add an observation of ...
Click on this link to add an observation of the plant using Plant Observation Entry.

Observation Hotline
Click this link to bring up the Observation Hotline application, and see if any contributors have added observations of this plant with photos.

View ... in Google Earth
Click this link to bring up Google Earth showing the same data. Lines and polygons are included when available.

BACKGROUND LAYERS

See also About Layers. When you choose a background layer such as Watersheds, the application will report the name of the watershed where the center mark is located. Click on the various watersheds to see their names.

If the Precipitation background layer is showing, you can click on the map to see average annual precipitation at that point .

Super Planning Watershed:
Tassajara Hot Springs 3309.6003
SHAPES and ICONS


Polygon data is available for a few plants, mostly weeds. If data is available, a Polygons checkbox appears. Check this box, and the available shapes will be drawn on the map. Shapes appear as shown on the right. Note that most polygons are tiny, so that you must zoom way in to see them. Switch the map to Satellite to zoom very close.

 

Polygon observations are indicated by a pink circle.

Point observations are indicated by a purple circle.

If surveys or checklists are available for this plant, they are indicated by a green square. If you do not want to see checklists, you can turn them off.

For certain plants (eg. rare plants in the CNPS Inventory), quad data is available. A quad is a USGS quadrangle, or 1/64 of a square degree. A quad record means that the plant has been found somewhere within that quad. Quads are indicated by a yellow square. If you do not want to see quads, you can turn them off.
POLYGON EXAMPLES
DESIGN
It is a challenge to come up with a straightforward method to visualize the distribution of a plant -- a method that gives useful information at various scales, from the whole state to very local.

An earlier version of this application followed the approach of a variable size grid (see graphic, right). One difficult aspect of this approach was how much subjectivity was involved in choosing the cell size. If you chose too large of a cell size, it appeared that the plant grew almost everywhere, and that the various populations were contiguous. If you chose a too small of a cell size, it appeared that the various populations were isolated from each other.

The Current Approach
In this version, there are no more cells. Instead, the application uses CalWater super planning watershed polygons to indicate presence. The state is divided into 2300 super planning watershed polygons.

The presence of the plant in a watershed is considered confirmed (yellow) if there are two or more observations in the watershed. The presence of the plant in a watershed is considered possible (orange) if there is a single observation in the watershed, or if there are several observations in the encompassing hydrologic area.

Limitations:
    Too Much Apparent Coverage

    1. A watershed polygon is highlighted because of a single record, and the record turns out to be erroneous.
      Check confirmed range to highlight only watersheds with two or more observations of the plant.

      If this situation comes up, please click through to RECORD DETAIL and put a comment on the record, or just write an email to Calflora about the problem.

    2. A huge watershed polygon is highlighted because of a single verified record at one end.
      Because the whole polygon is highlighted, it gives the impression that the plant is present throughout, whereas all we really know is that it is present at one end. If huge watershed polygons were split into smaller pieces, that would present a more accurate view.

    3. A watershed polygon encompasses a signifigant elevation differential, and has only a single verified record at one end of the elevation range.
      Because the whole polygon is highlighted, it gives the impression that the plant is present at all elevations; in fact, the plant may only grow in a narrow elevation range. If such watershed polygons were split into smaller pieces on the basis of elevation, that would present a more accurate view with respect to elevation.

    Too Little Apparent Coverage

    1. Some of the watershed polygons are tiny, particularly in the coast ranges. Because of the randomness of the observations, the map has a speckled appearance, with some tiny watersheds highlighted, and some not highlighted.
      In the CalWater watershed hierarchy, the containing unit for super planning watershed is hydrologic area. As of version 2.03, if there are many super planning watersheds in a single hydrologic area which contain observations of the plant, then the whole hydrologic area is displayed as possible range. In many cases this reduces the speckled appearance.

    2. It would be helpful to be able to see where a plant might grow, based on elevation and climate data, in addition to where it has actually been seen growing.
We have started to work on these issues. If you have suggestions, please let us know.
RELEASE NOTES:

• November, 2017:   v. 2.03 If there are several super planning watersheds in the same hydrologic area that have observations of the plant, then all of the super planning watersheds in that hydrologic area are considered to be possible range and colored orange.

• November, 2017:   v. 2.02 The possible range is differentiated from the confirmed range. A user can choose to see just the confirmed range.

• October, 2017:   v. 2.00