Answer:
The sporangiophore grow vertically which is in an upward direction because it is positively phototrophic. This means that it grows towards the ray of light from the sun which is found above. This is usually due to the provision of solar(light) energy from the sun which is used for the photosynthetic processes of the plants
The rhizoides grow downwards because they are positively geotrophic. This means they grow according to the force of gravity which acts downwards.