If I take the word "directly" as the key here, that is without using a powered USB hub, then the answer is "it depends".
You see with a maximum input current of about 1.1 Amp, and a own consumption of about 0.7A, the PI can only provide its two USB ports with 1 - 0.7 = 0.3Amp, or 300mA, so only if all your USB devices (plus potentially the HDMI port) together draw less than 300mA it could Work, IF your power supply is up to the task.
Assuming you are only using a normal USB keyboard, and a normal HDMI cable to a HDMI monitor, they together will consume about 100mA, which means there is only 200 or so mA left for the WiFi module, which could be a problem, as most of them need more than that to work reliable (that is, even when momentarily more power is needed than on average, the maximum is still below 200mA).
For a reliable WiFi connection a powered USB hub is really almost a prerequisite, the FAQ also mentions this.
If you need to connect a USB device that will take the power requirements of the Raspberry Pi above 1 Amp then you must connect it to an externally powered USB hub.