Simple equations whose plot looks like field grass

Math Overflow has an interesting question about unexpected mathematical images. Here's a response from Payam Seraji that was easy to code up.

Here's the code that produced the image.

from numpy import *import matplotlib.pyplot as pltt = linspace(0, 39*pi/2, 1000)x = t*cos(t)**3y = 9*t*sqrt(abs(cos(t))) + t*sin(0.2*t)*cos(4*t)plt.plot(x, y, c="green")plt.axes().set_aspect(0.3)plt.axis('off')

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