Kind of hard to tell from the photos but willow - Genus Salix has twigs and leaves that alternate as you go up or down the shoot. Dogwood - genus Cornus has twigs that occur in paired, opposite and then the next paired opposite set is at right angles to the previous one. They alternate in this pattern. The veins on the leaves are paired from a mid line. Ash, viburnum, privet, maple and lilac have a similar alternating pair, opposite pattern. How lucky you would be if the plant is arrowwood viburnum. Second growth shoots and bow staves that come off a stump of a large tree are very desirable because they are being nourished by a large and well established root system and will be vigorous. May I suggest that you go to the local library and check out a plant and shrub identification book or buy a used one from a bookstore. That way you'll have it to carry afield. If the arrow wood in question will make good shafts and you have permission to cut them, by all means gather some now as it will be too late for ideal harvesting once the leaves are developed. A good rule of thumb for arrow shoots in the Northern Hemisphere is to gather between Thanksgiving and Valentine's Day. Until next time, Go to the woods. Walk softly, And carry a bent stick.